Wall Plug Guide: Nylon Anchors, Frame Fixing, Plasterboard Fixings & Substrate Selection

A wall plug is a nylon, polyethylene, or PVC anchor that goes into a drilled hole in masonry, brick, concrete or other substrate so that a screw can grip and hold a fixing to the wall. Without the plug, the screw has nothing to grip — masonry is too hard for the screw thread to cut itself into, and most softer substrates don't have enough thickness for a screw thread alone to support load. The plug bridges the gap: it converts a hard masonry surface into something a screw can anchor to.

Wall plugs are the most-used fastener anchor in Australia by unit count — every picture frame, every shelf bracket, every door handle, every electrical fitting, every plumbing wall mount uses a wall plug or a wall plug equivalent. They're cheap, they're available everywhere, they install in minutes with a hammer drill and a screwdriver, and they work reliably when matched to the right substrate.

The single biggest cause of wall plug failure customers experience is using a standard nylon plug in plasterboard. Plasterboard has no compressive strength to grip the plug's expansion force — the plug simply widens the hole and falls out. This guide covers the substrate-matching rules, the colour-size-drill chart that almost no AU customer correctly remembers, the Mungo frame-fixing technology that makes perforated brick and aerated concrete work, the plasterboard-specific anchor alternatives (WallMate, toggle, Molly bolt, stud-fix), and the practical workshop discipline that determines whether a wall plug grips for 30 years or pulls out the first time a load is applied.

AIMS Industrial stocks wall plugs and nylon plugs across three supply tiers: Mungo (Swiss-made premium frame fixings with Quattro Technology — AIMS is an authorised Mungo distributor; the MB-S, MB-ST, MQL-ST and MQL-SS frame plug series are the trade-grade choice for perforated brick, aerated concrete and frame-fixing service); Hobson Universal (workshop value tier — tapered-point nylon plugs in 8mm and other standard sizes, plus blue PVC plugs for light-duty); and specialty plasterboard plugs (Hobson #8 nylon plasterboard plug for the specific drywall service that standard wall plugs can't handle).

This guide is a spoke from our Concrete & Masonry Anchor Guide, which covers the 6-family anchor architecture (sleeve, wedge, drop-in, screw, plug, chemical). For chemical resin anchor service see our Chemical Anchor Guide; for high-load wedge and sleeve anchors see the main Concrete & Masonry Anchor Guide.

What is a wall plug and how does it work

A wall plug is a hollow nylon (or polyethylene/PVC) sleeve, typically 20-50mm long with longitudinal slots cut along most of its length. The plug's outside diameter matches the diameter of a drilled hole; the screw's diameter is matched to the plug's bore. When the screw is driven into the plug, the screw threads cut into the inner bore of the plug; the plug body expands radially outward through the longitudinal slots, gripping the walls of the drilled hole. The expanded plug now anchors the screw, and the screw can carry load.

The mechanism has four critical components:

1. The drilled hole — straight, correct diameter for the plug, correct depth, clean of dust. Mismatched here and the plug doesn't grip.
2. The plug itself — matched diameter, matched expansion characteristics to the substrate, undamaged.
3. The screw — matched gauge to the plug, sufficient length to bottom out in the plug, correct head type for the fixing.
4. The substrate — sufficient compressive strength to resist the plug's expansion force without crushing or fragmenting.

When any one of these four components is wrong, the assembly fails. Most failures customers experience trace back to substrate mismatch (plasterboard, hollow blockwork) or hole-prep failure (oversized hole, dust contamination). Material specification is rarely the issue once you're past the cheap-vs-quality threshold.

Wall plug vs masonry anchor vs screw anchor

Wall plugs are one category of masonry fixing among several. The full family is covered in our Concrete & Masonry Anchor Guide; below is the short version that explains where wall plugs fit.

Wall plugs sit at the light-to-medium load end of the masonry anchor spectrum. Above 50 kg per fixing, step up to screw anchors or sleeve anchors. Below 5 kg, a wall plug may be overkill — a hammer-drive plug or self-tapping concrete screw works for light fixtures. For plasterboard, a wall plug is the wrong category entirely — use a dedicated plasterboard anchor.

The wall plug colour-size system — yellow, red, brown, blue

Wall plugs follow a colour-coded sizing system that originated with the UK Rawlplug brand and is now used across most AU and global manufacturers. The colour tells you the plug diameter, the matching screw gauge range, and the drill bit size you need.

The colour system is a convention, not a rigid standard — some brands offer additional sizes (green at 3mm for very light fixings, grey at 12mm for heavy duty) and some use slightly different colour-size mappings. Always confirm against the packaging before drilling.

Substrate selection — solid brick, perforated brick, AAC, blockwork

Substrate selection is the most important decision in wall plug specification — get this wrong and even the best plug fails. The substrate determines whether a standard plug works at all, and whether you need a frame-fixing plug, a Quattro-technology plug, or an entirely different anchor.

The decision rule: solid masonry → any standard plug; perforated brick → frame plug; aerated concrete → Quattro frame plug; plasterboard → dedicated plasterboard anchor. Identifying the substrate before drilling is more important than picking the "best" plug — the right product for the wrong substrate fails just as fast as the wrong product.

Plasterboard — never use a standard wall plug

Plasterboard requires anchors designed specifically for hollow-wall service. Four categories of plasterboard anchor cover different load ranges:

1. Self-drilling plasterboard plug (WallMate-style) — typically a plastic or metal threaded plug that screws directly into plasterboard with a Phillips screwdriver. No pilot hole needed. The plug's threads engage the gypsum and paper, distributing load over a wider area than an expansion plug. Rated 5-10 kg static load typical. Hobson stocks #8 nylon plasterboard plugs.
2. Spring toggle anchor — folded metal wings on a threaded shaft. Insert through a drilled hole; the wings spring open behind the plasterboard, then pull tight against the back surface as the screw is driven. Highest static load capacity for plasterboard — typically 15-30 kg per anchor.
3. Molly bolt / hollow wall anchor — metal sleeve with expansion legs that fold open against the back of the plasterboard as the central screw is tightened. Permanent installation (removing the bolt leaves the sleeve in the wall). Very high grip, but visible in the wall after removal.
4. Stud fix (direct to timber) — locate the timber stud behind the plasterboard with a stud finder or knock test, and screw directly into the timber. No anchor needed; load capacity is the shear strength of the screw thread in timber. Always the preferred approach for fixings over 10 kg.

For any plasterboard fixing over 5 kg, stud-fix is the recommended approach. For lighter fixings (picture frames, small shelves), self-drilling plasterboard plugs are easier than locating studs. Avoid using more than one plasterboard anchor on the same fixing — the load is rarely distributed evenly and the highest-loaded anchor tends to fail first, then the rest cascade.

Universal wall plugs — what makes them "universal"

The "universal" designation on a wall plug refers to the plug's ability to work across multiple substrate types — solid brick, concrete, and (with appropriate care) light hollow blockwork and certain perforated substrates. Universal plugs typically have a tapered point for easier insertion, multiple longitudinal expansion slots (rather than a single slot), and a knotting action where the plug deforms internally as it expands externally.

The Hobson 8mm Universal Wall Plug — tapered point, nylon grey, 40mm length — is the AIMS workshop value-tier universal plug. Standard fixing for general workshop and trade use across most solid masonry substrates. Stocked in 500-piece packs for high-volume use.

Universal plugs are not a substitute for proper substrate-specific selection in critical applications. For perforated brick service the Mungo MB-ST frame plug is engineered specifically — the universal plug works but with lower load capacity. For aerated concrete (Hebel) the Mungo MQL-ST Quattro is purpose-designed — the universal plug typically fails in AAC.

The rule: universal plugs cover the 70% case (general solid masonry, light loads); substrate-specific plugs cover the 30% case where load, substrate weakness, or critical fixing matters.

Frame fixing plugs — the long anchor architecture

Frame fixing plugs are extra-long nylon anchors (typically 80mm to 280mm long) designed to fasten window frames, door frames, timber battens, and external cladding to masonry behind in a single pass. The advantage over standard plug-and-screw assembly: you drill once through the frame and into the substrate, insert the assembled plug-and-screw together, and drive the screw. No need to position the plug separately, no need to drill the frame and substrate as separate operations, no risk of the plug moving out of alignment with the frame hole.

Mungo's frame fixing range covers most AU construction needs:

Length range across the Mungo frame fixing series spans 80mm to 280mm — long enough to anchor through 100mm timber frames into block walls behind, or through 50mm furring strips into structural masonry. The screws ship assembled to the plug for single-operation installation.

Mungo Quattro Technology — 4 expansion zones for perforated brick + AAC

The Mungo MQL series uses what Mungo calls "Quattro Technology" — the plug has four distinct expansion zones distributed along its length, each capable of expanding independently to grip the substrate at four separate depths. Standard wall plugs have a single expansion zone near the back of the plug; Quattro plugs grip at four points.

The engineering reason: in perforated brick (modern AU residential construction increasingly uses cavity-section bricks) and aerated concrete (Hebel block), the substrate is alternating layers of solid material and voids. A standard single-expansion plug may land entirely in a void — grip-free, useless. Quattro Technology distributes the expansion across four zones, virtually guaranteeing that at least 2-3 zones land in solid substrate material regardless of where the plug sits in the brick or block.

Result: Mungo MQL plugs deliver typical load capacity of 0.5-1.5 kN per fixing in perforated brick (where standard plugs are unreliable at any load) and 0.3-0.8 kN in aerated concrete (where standard plugs typically fail at any meaningful load). The Quattro plug is the engineered solution to the modern AU masonry substrate reality.

This technology premium is the reason trades pay more for Mungo than for generic Chinese-made plugs in perforated brick and AAC applications. The plug pays for itself the first time it grips where a generic plug would have failed.

Hole preparation — depth, dust, drill straight

Hole preparation discipline is the difference between a wall plug that grips for 30 years and one that fails on first load. The four critical rules:

1. Drill diameter matches plug diameter — yellow plug 5mm, red 6mm, brown 7mm, blue 10mm. Use masonry drill bits with carbide tips on a hammer drill setting; avoid HSS twist drills in masonry (they dull fast).
2. Hole depth = plug length + 10mm — extra depth provides clearance for the plug end and accommodates dust compaction at the bottom of the hole. A plug that bottoms out before fully inserting can't expand properly.
3. Drill straight, perpendicular to the wall — angled holes cause the plug to expand unevenly, with one side gripping and the other loose. Use a level or square against the drill to maintain perpendicular alignment.
4. Clear dust from the hole before inserting the plug — vacuum, blow with compressed air, or pull a brush through the hole. Even a thin dust layer prevents the plug from gripping the substrate walls. Tradies use a small bicycle pump to blow out dust on site.

The hole-prep discipline is the practitioner skill that separates reliable installations from failures. Most cheap plugs in clean holes outperform expensive plugs in dusty oversized holes.

Installation procedure — drill, clean, insert, drive

Standard installation procedure for any wall plug + screw assembly:

1. Mark and check — mark the hole location; check it's not on a mortar joint, a wiring channel, or a plumbing run. Use a stud finder or electrical detector for plasterboard service.
2. Select the plug — match plug colour to load (yellow 4mm, red 6mm, brown 7mm, blue 10mm). Match the matching screw gauge to the plug specification.
3. Drill the hole — masonry drill on hammer setting; plug-diameter bit; depth = plug length + 10mm; straight perpendicular alignment.
4. Clear the hole — vacuum or blow out dust completely. Tap a drill bit shaft into the hole — if it comes out dusty, blow it out again.
5. Insert the plug — push the plug into the hole flush with the substrate surface. The plug should slide in by hand with light thumb pressure. If it requires hammering, the hole is too small (redrill with the correct bit). If it falls in loose, the hole is too large (move to a new location or step up plug size).
6. Position the fixing — bracket, frame, or fixture against the wall with the plug hole aligned to the fixing hole.
7. Drive the screw — through the fixing and into the plug. Drive until the screw head is flush against the fixing; don't over-tighten — over-driving strips the plug threads and the plug stops gripping.

For frame fixing plugs (Mungo MB and MQL series), the procedure is simpler — drill through the frame and into the substrate in a single hole, insert the assembled plug-and-screw, drive home with a power driver. No separate plug-positioning step.

Plug spinning in hole — diagnosis and the spaghetti trick

"My plug is spinning in the hole" is the most-Googled wall plug failure question. The diagnosis is straightforward — one of three root causes:

1. Hole too large for plug — drill bit oversized (worn bit, wrong size, drill ran in the hole creating an oversized cavity). Plug doesn't grip the walls; spins or falls out under screw load. Fix: redrill at a new location with correct bit size.
2. Substrate too weak — plasterboard, mortar joint, weak brick, void in hollow blockwork. Plug expands but substrate yields. Fix: switch to plasterboard-specific anchor, or move the hole to solid brick face, or step up to a frame plug for hollow brick.
3. Dust contamination — fine masonry dust prevents the plug from gripping. Fix: clear the hole thoroughly before reinserting plug.

The DIY forums and Whirlpool tradie threads consistently surface what's called "the spaghetti trick" — stuffing toothpicks, matchsticks, BBQ skewers, or strips of plastic ("spaghetti" — the trade nickname for any soft filler) into an oversized hole to bulk it out before inserting the plug. It's a recurring topic and views are divided: some swear by it for emergency fixes ("I've used the matchstick trick for 30 years"); others — engineers, professional tradies, and us — point out that the fix is unreliable, doesn't restore proper expansion grip, and almost always pulls out under any meaningful load.

The proper fix for an oversized hole is one of:

• Move to a new location with a fresh correctly-sized hole — 50mm offset is usually enough to avoid the damaged area.
• Step up to a larger plug — red plug → brown plug → blue plug, with corresponding drill upsizing. A brown plug grips fine in a hole originally drilled for red.
• Switch to a chemical anchor — for critical fixings where neither relocation nor upsizing works, our Chemical Anchor Guide covers resin-bonded anchors that work in oversized or damaged holes.

The spaghetti trick has its devotees but it's a hack, not a fix. For any load over 5 kg, do the job properly.

AAC / Hebel / aerated concrete service — specific plug selection

Aerated autoclaved concrete (AAC) — sold under the Hebel brand in Australia — is a lightweight masonry block with high air void content. The structure is uniformly cellular: tiny air bubbles throughout the block matrix, giving Hebel its insulation properties and light weight. The downside for fixings: the compressive strength is much lower than solid brick (typically 3-5 MPa vs 15-25 MPa for clay brick), and the cellular structure means a standard wall plug's expansion force simply crushes the substrate locally rather than gripping it.

For AAC service, the plug must distribute expansion force across a wider area:

• Mungo MQL-ST Quattro Technology — the engineered solution. Four expansion zones grip at four depths; cumulative grip area is 4× a standard plug. Specifically tested and rated for AAC service.
• Long frame fixings (Mungo MB series 100mm+) — distributed grip along the full plug length, suitable for AAC when Quattro isn't available.
• Chemical anchor — for higher loads, our Chemical Anchor Guide covers chemical-injected anchors that work in AAC.

The decision rule for AAC: Mungo MQL-ST Quattro as default. For loads above ~5-10 kg per fixing, step up to chemical anchor. Don't use generic wall plugs in AAC — they may grip on initial install but pull out within months under typical load cycling.

Cement sheet + villaboard — AU wet-area requirements

Cement sheet (also called fibre cement sheet, FC sheet, or villaboard for wet-area applications) is a common AU lining material in bathrooms, laundries, and external eaves. It's typically 6-12mm thick, denser than plasterboard but softer than masonry. Standard wall plugs typically crack cement sheet on insertion because the substrate flex during plug expansion exceeds the sheet's tensile strength.

For cement sheet service:

• Mungo MQL-ST Quattro distributed-expansion plug — distributes force across 4 zones to avoid concentrated stress.
• Plasterboard-style anchors — self-drilling plasterboard plugs work in cement sheet for light loads; spring toggle anchors for heavier loads.
• Stud fix where possible — locate the timber stud or steel furring behind the cement sheet and screw directly.

For wet-area service (bathroom, laundry, outdoor eaves), corrosion resistance matters — specify zinc-plated screws minimum, or stainless steel screws (304 for general wet area, 316 for coastal/marine). Standard mild steel screws fail by corrosion in wet-area service within 5-10 years.

Hammer-in plugs and quick fixings

For light fixings that don't need disassembly, hammer-in plugs (also called masonry strap plugs or drive-in fixings) speed up installation. The plug and screw ship as a single assembly; you drill the hole, insert the plug-screw assembly, and drive it home with a hammer. The screw is permanent — it can't be unscrewed to remove the fixing later, only cut off.

Typical applications: cable clips along masonry walls, light brackets, conduit fixings, fence palings to brick. Quick installation, no screwdriver needed, but no disassembly possible. Hobson and Mungo both offer hammer-in plug variants.

For removable fixings or anywhere disassembly might be needed, use a standard plug-and-screw combination. The 30-second saved on installation isn't worth losing the option to remove the fixing later.

Load capacity by plug size + substrate

Wall plug load ratings are notoriously inconsistent across manufacturers and substrates. The figures below are typical static load capacities; dynamic loads (shock, vibration) reduce these by 50-70%. Always apply a safety factor of 3-5× working load to plug rated capacity for normal service.

These figures are per fixing. Multi-fixing assemblies (shelves with 2+ plugs, large brackets) distribute load across multiple plugs — but never assume even distribution; size each plug for at least the highest-loaded fixing, not the average load. The first plug to fail triggers a cascade as load shifts to remaining plugs.

Removing a wall plug — when it can be done, when it can't

Removing a wall plug after installation depends on what's in the hole. Three scenarios:

1. Plug only (no screw inserted) — pull out with pliers, or extract with a corkscrew-style plug puller (cheap tool, screws into the plug bore and pulls it out as it threads in). Easy.
2. Plug + screw, screw can be unscrewed — unscrew the screw fully; the plug then pulls out or stays in the hole depending on how tight the original installation was. Often the plug pulls out with the screw, leaving a clean hole.
3. Plug + screw, screw seized (corrosion, paint over, stripped head) — drill out the screw with a left-hand cobalt drill bit (sometimes the drilling action backs the screw out), or cut the screw head flush with the wall and leave the plug + screw shaft buried. Patch over the visible hole.

For wall plugs flush with the substrate surface that won't pull out: drill the plug bore out with a slightly smaller drill bit (5mm drill in a yellow plug, 6mm in a red), break the plug walls into small pieces, vacuum out. Hole can be re-used with a fresh same-size plug, or patched with masonry filler if not reusing.

AIMS wall plug supply — Mungo + Hobson + universal range

Pairing wall plugs with companion products: Concrete & Masonry Anchor Guide for the broader anchor architecture, Chemical Anchor Guide for high-load resin-bonded alternatives, Self-Tapping Screws Guide for direct-into-substrate options (Tek screws for steel, concrete screws for masonry), Drill Bit Types Guide for the masonry drill bits needed for hole prep.

For specialty applications outside standard stock — fire-rated plugs for fire-stopping service, extra-long frame fixings beyond 280mm, stainless steel frame fixings for marine/coastal exposure — AIMS sources through our Mungo authorised distributor network. Contact us or call (02) 9773 0122 with the application (substrate, load, environment, fixing geometry) and we'll specify the right plug for the duty.

Common wall plug mistakes — diagnostic table

Frequently Asked Questions

What size drill bit do I need for a wall plug?

The drill bit size matches the plug size, not the screw size. Yellow plug = 5mm drill. Red plug (the workshop default) = 6mm drill. Brown plug = 7mm drill. Blue plug = 10mm drill. This is the #1 wall plug installation mistake — using a screw-sized drill makes the hole too small for the plug, which then jams or splits on insertion.

What's the difference between yellow, red, brown and blue wall plugs?

The colour indicates plug diameter and the matching screw gauge range. Yellow ≈ 5mm plug for No. 6-8 screws (light fixings). Red ≈ 6mm plug for No. 8-10 screws (workshop default). Brown ≈ 7mm plug for No. 10-14 screws (medium loads). Blue ≈ 10mm plug for No. 14-18 screws (heavy fixings). The colour-coding originated with the UK Rawlplug brand and is now industry standard across most manufacturers.

Can I use a wall plug in plasterboard?

No — standard nylon wall plugs do not work in plasterboard. Plasterboard has no compressive strength to resist the plug's expansion force; the plug widens the hole and pulls out. Use a plasterboard-specific anchor: self-drilling plasterboard plug (WallMate-style) for light fixings, spring toggle for medium loads, or Molly bolt for heavier loads. For loads over 5 kg, locate the timber stud and screw directly.

What is the best fixing for plasterboard?

For any fixing over 5 kg, locate the timber stud behind the plasterboard and screw directly into the timber — no anchor needed. For lighter fixings (under 5 kg), self-drilling plasterboard plugs are easiest. For 5-15 kg loads on plasterboard without a stud, use spring toggle anchors. For 15-30 kg, Molly bolts or multiple spring toggles. Above 30 kg, consider relocating to a stud.

How much weight can a wall plug hold?

Depends on plug size and substrate. Static load typical: Yellow 5-10 kg, Red 15-25 kg, Brown 30-50 kg, Blue 60-100 kg in solid brick or concrete. Mungo MQL-ST Quattro plug rates higher in difficult substrates. Apply 3-5× safety factor to rated capacity for working load. Dynamic loads (shock, vibration) reduce capacity by 50-70%.

What is a frame fixing plug?

An extra-long wall plug (typically 80-280mm) designed to fasten window frames, door frames, or timber battens through the frame and into the masonry behind in a single operation. Drill through the frame and into the substrate, insert the assembled plug-and-screw, drive the screw. Mungo MB and MQL series are the trade-grade frame fixing range.

What is a Mungo plug?

Mungo is a Swiss-made premium nylon plug brand — the trade-grade choice for perforated brick, aerated concrete, frame fixing, and other demanding substrates. AIMS is an authorised Mungo distributor. The MB series covers standard frame plugs; the MQL series adds Quattro Technology with 4 expansion zones for difficult substrates (perforated brick, AAC, cement sheet).

What is Quattro Technology?

Mungo's MQL plug series uses four distinct expansion zones distributed along the plug length, each capable of expanding independently to grip the substrate at four separate depths. Designed for perforated brick and aerated concrete (Hebel/AAC) where a single-expansion-zone plug might land entirely in a cavity. Quattro virtually guarantees 2-3 zones land in solid substrate regardless of plug position.

What is a universal wall plug?

A nylon plug designed to work across multiple substrate types — solid brick, concrete, light hollow blockwork, certain perforated substrates. Universal plugs typically have a tapered point, multiple longitudinal expansion slots, and a knotting action. The Hobson 8mm Universal Wall Plug is the AIMS workshop value-tier choice. Not a substitute for substrate-specific plugs in critical applications.

Why does my wall plug spin in the hole?

Three causes: hole too large for the plug (drill bit oversized, or drilling action enlarged the hole), substrate too weak (plasterboard, mortar joint, hollow void), or dust contamination preventing grip. Fix: move to a new location with correct hole size, or step up plug size, or switch to substrate-specific anchor. Avoid the "spaghetti trick" of stuffing matchsticks or filler in — it's unreliable and pulls out under load.

How deep should I drill for a wall plug?

Hole depth = plug length + 10mm. The extra depth provides clearance for the plug end and accommodates dust at the bottom of the hole. A plug that bottoms out before fully inserting can't expand properly and won't grip reliably.

Can I use a nylon plug in aerated concrete (Hebel)?

Standard nylon plugs typically fail in AAC because the cellular structure crushes locally rather than gripping. Use Mungo MQL-ST Quattro Technology plugs — the 4 expansion zones distribute force across the AAC matrix and grip reliably. For loads above ~5-10 kg per fixing, consider chemical anchors instead. See our Chemical Anchor Guide for higher-load AAC service.

What size screw goes with each plug colour?

Yellow plug: No. 6-8 screws (~3.5-4mm). Red plug: No. 8-10 screws (~4-5mm). Brown plug: No. 10-14 screws (~4.5-6mm). Blue plug: No. 14-18 screws (~6-8mm). Match screw gauge to the range specified on the plug packaging — too small a screw won't grip the plug bore; too large will split the plug on insertion.

How do I remove an old wall plug?

If the plug is empty (no screw): pull out with pliers or use a corkscrew-style plug puller. If the plug has a screw: unscrew the screw — often the plug pulls out with it. If the screw is seized: drill out with a left-hand cobalt bit, or cut the screw head flush and leave the buried plug + screw shaft in place. For flush plugs that won't pull out: drill the plug bore out with a slightly smaller drill bit, break the plug walls, vacuum debris.

What's the difference between a wall plug and a screw anchor?

A wall plug is a nylon expansion anchor designed for a separate screw — the plug grips the masonry, the screw grips the plug. A screw anchor (masonry screw, concrete screw) is a one-piece self-tapping screw that cuts its own thread directly into masonry without a plug. Wall plugs are cheap and re-usable for ad-hoc fixings; screw anchors give higher load capacity and faster installation but are typically more expensive per unit.

Sizing fasteners across systems? Our Fastener Reference Guide shows the imperial equivalents for every common metric thread and vice versa.