--- title: "What Are Hollow Wall Anchors (Molly Bolts) Used For?" description: "Hollow Wall Anchors (Molly Bolts) (Trade series (metal cavity anchor)) are used for fixing steelwork, plant and services to concrete and masonry, where the a…" url: https://engineeringhardware.com/applications/hollow-wall-anchors/ source: Engineering Hardware & Fasteners --- # What Are Hollow Wall Anchors (Molly Bolts) Used For? Anchors & Concrete Fixings · Trade series (metal cavity anchor) · Application guide Typical applications, the industries that specify hollow wall anchors (molly bolts), and how to choose the right size, material and finish for the joint. Hollow Wall Anchors (Molly Bolts) are used for fixing steelwork, plant and services to concrete and masonry, where the anchor is set in a drilled hole and its capacity is governed by the base material rather than by the steel. They are manufactured to Trade series (metal cavity anchor), and selection is driven by the thread size, the fit and tolerance the assembly requires, and the service environment. - **Primary duty:** Fixing steelwork, plant and services to concrete and masonry, where the anchor is set in a drilled hole and its capacity is governed by the base material rather than by the steel - **Governing standard:** Trade series (metal cavity anchor) - **Thread size range:** M4 to M6 - **Category:** Anchors & Concrete Fixings Application notes are general engineering guidance. Verify the property class and any approval requirement against your own design calculation. ![What Are Hollow Wall Anchors (Molly Bolts) Used For? application image](https://engineeringhardware.com/wp-content/uploads/2026/08/Hollow-Wall-Anchors.webp) Application guide for Hollow Wall Anchors (Molly Bolts) to Trade series (metal cavity anchor). The core duty of the type is fixing steelwork, plant and services to concrete and masonry, where the anchor is set in a drilled hole and its capacity is governed by the base material rather than by the steel. The typical industries, the how-to-specify checklist, assembly practice and the exclusion cases are set out below. Stocked across roughly M4 to M6, they cover light-duty and instrument-scale work. ## Typical Applications for Hollow Wall Anchors (Molly Bolts) The most common settings where these are specified: - **Fit-out & drylining:** fixing to plasterboard, block and hollow wall where there is no solid backing. - **General machine building:** fastening covers, brackets, motors and sub-assemblies on production equipment. - **Maintenance & repair (MRO):** a stocked size for servicing existing plant where the original fastener spec must be matched. - **Fabrication & metalwork:** bench and on-site assembly of steel frames, enclosures and weldments. - **Structural fixing to concrete:** base plates, brackets, rails and steelwork bolted to a concrete slab or wall. Product catalog ## Related Hollow Wall & Toggle Anchors products [![L-Type O/Eye-Type Carbon Steel Stainless Steel Hollow Wall Plasterboard Fixing Anchor](https://img.engineeringhardware.com/L-Type-O-Eye-Type-Carbon-Steel-Stainless-Steel-Hollow-Wall-Plasterboard-Fixing-Anchor.webp)](https://engineeringhardware.com/product/l-type-o-eye-type-carbon-steel-stainless-steel-hollow-wall-plasterboard-fixing-anchor/) Hollow-Wall & Toggle Anchors ### [L-Type O/Eye-Type Carbon Steel Stainless Steel Hollow Wall Plasterboard Fixing Anchor](https://engineeringhardware.com/product/l-type-o-eye-type-carbon-steel-stainless-steel-hollow-wall-plasterboard-fixing-anchor/) Round Head · DIN, ANSI, GB, JIS, BSW, GOST **US$0.012 – 1.20**MOQ 10,000 pieces [![3/16 in. X 2 in. Plasterborad Toggle Bolts Round Head Spring Wing, Zinc Plated Carbon Steel](https://img.engineeringhardware.com/3-16-in-X-2-in-Plasterborad-Toggle-Bolts-Round-Head-Spring-Wing-Zinc-Plated-Carbon-Steel.webp)](https://engineeringhardware.com/product/3-16-in-x-2-in-plasterborad-toggle-bolts-round-head-spring-wing-zinc-plated-carbon/) Hollow-Wall & Toggle Anchors ### [3/16 in. X 2 in. Plasterborad Toggle Bolts Round Head Spring Wing, Zinc Plated Carbon Steel](https://engineeringhardware.com/product/3-16-in-x-2-in-plasterborad-toggle-bolts-round-head-spring-wing-zinc-plated-carbon/) Spring Togger · DIN, ANSI **US$0.30 – 1.20**MOQ 10,000 length [![M6 M7 M8 Stainless Carbon Steel Heavy Duty Hollow Wall Expansion Bolt Spring Butterfly Toggle Bolt Drywall Anchor](https://img.engineeringhardware.com/M6-M7-M8-Stainless-Carbon-Steel-Heavy-Duty-Hollow-Wall-Expansion-Bolt-Spring-Butterfly-Toggle-Bolt-Drywall-Anchor.webp)](https://engineeringhardware.com/product/m6-m7-m8-stainless-carbon-steel-heavy-duty-hollow-wall-expansion-bolt-spring/) Hollow-Wall & Toggle Anchors ### [M6 M7 M8 Stainless Carbon Steel Heavy Duty Hollow Wall Expansion Bolt Spring Butterfly Toggle Bolt Drywall Anchor](https://engineeringhardware.com/product/m6-m7-m8-stainless-carbon-steel-heavy-duty-hollow-wall-expansion-bolt-spring/) Round Head · DIN, ANSI, GB, JIS, BSW, GOST **US$0.13 – 0.16**MOQ 3,000 pieces [![Carbon Steel Hollow Wall Heavy Duty Plug Drywall Gecko Expansion Bolt](https://img.engineeringhardware.com/Carbon-Steel-Hollow-Wall-Heavy-Duty-Plug-Drywall-Gecko-Expansion-Bolt.webp)](https://engineeringhardware.com/product/carbon-steel-hollow-wall-heavy-duty-plug-drywall-gecko-expansion-bolt/) Hollow-Wall & Toggle Anchors ### [Carbon Steel Hollow Wall Heavy Duty Plug Drywall Gecko Expansion Bolt](https://engineeringhardware.com/product/carbon-steel-hollow-wall-heavy-duty-plug-drywall-gecko-expansion-bolt/) Stainless Steel · 4.8 **US$0.072 – 2.40**MOQ 10 pieces [![Heavy-Duty Butterfly Toggle Anchor for Maximum Load Support](https://img.engineeringhardware.com/Heavy-Duty-Butterfly-Toggle-Anchor-for-Maximum-Load-Support.webp)](https://engineeringhardware.com/product/heavy-duty-butterfly-toggle-anchor-for-maximum-load-support/) Hollow-Wall & Toggle Anchors ### [Heavy-Duty Butterfly Toggle Anchor for Maximum Load Support](https://engineeringhardware.com/product/heavy-duty-butterfly-toggle-anchor-for-maximum-load-support/) Hexagon Head · DIN, GB, ANSI, BSW, JIS, GOST **US$0.012**MOQ 100 pieces [![Carbon Steel Spring Toggle Bolt Anchor](https://img.engineeringhardware.com/Carbon-Steel-Spring-Toggle-Bolt-Anchor.webp)](https://engineeringhardware.com/product/carbon-steel-spring-toggle-bolt-anchor/) Hollow-Wall & Toggle Anchors ### [Carbon Steel Spring Toggle Bolt Anchor](https://engineeringhardware.com/product/carbon-steel-spring-toggle-bolt-anchor/) SS410,SS304, SS316 · 2008, SGS testing report & RoHS **US$0.12 – 1.20**MOQ 1,000 pieces [View all Hollow-Wall & Toggle Anchors →](https://engineeringhardware.com/fastener-products/anchors-construction-fixings/hollow-wall-toggle-anchors/) [Full product catalog](https://engineeringhardware.com/products/) ## How to Specify Hollow Wall Anchors (Molly Bolts) for Your Application - **Size:** Match the nominal size to the mating thread or hole. This product spans M4–M6; check the full table below for the exact dimensions of each size. - **Material:** Choose the material and finish for the service environment — plated steel for general use, stainless for corrosion resistance. - **Environment:** For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient. - **Standard:** This product is supplied to Trade series (metal cavity anchor). Quoting the standard on your order guarantees interchangeable dimensions between suppliers. ## Where Hollow Wall Anchors (Molly Bolts) Are Not the Right Choice Match the fastener to the load, environment and whether the joint must be reopened; the wrong class or style is the usual cause of joint failure. Custom manufacturing · Made to drawing ## Need a hollow wall anchors (molly bolts) outside the standard range? Length and corrosion protection are the usual specials. The load a fixing will take is decided by the concrete and the edge distance, not by ordering a longer anchor. Made by hot forging or thread rolling. Minimum order from 2,000 pieces; samples within 7 days of drawing approval. [Custom anchor & concrete fixing manufacturing](https://engineeringhardware.com/custom/anchors/)[Send a drawing](https://engineeringhardware.com/custom/anchors/#rfq) ## Technical Drawing Dimensioned line drawing of M4 Hollow Wall Anchors (Molly Bolts) to Trade series (metal cavity anchor). Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected. - **Drill hole diameter (mm):** 8 - **Wall thickness range (mm):** 3~13 - **Anchor length (mm):** 32 - **Flange diameter (mm):** 11.0 - **Setting:** Screw-set / setting tool - **Material:** Zinc plated steel - **Screw retained:** Yes u2014 removable ## Dimensions & Specifications (Trade series (metal cavity anchor)) | Screw size | Drill hole diameter (mm) | Wall thickness range (mm) | Anchor length (mm) | Flange diameter (mm) | Setting | Material | Screw retained | | --- | --- | --- | --- | --- | --- | --- | --- | | M4 | 8 | 3~13 | 32 | 11.0 | Screw-set / setting tool | Zinc plated steel | Yes u2014 removable | | M5 | 10 | 5~20 | 38 | 13.0 | Screw-set / setting tool | Zinc plated steel | Yes u2014 removable | | M5 | 10 | 13~30 | 52 | 13.0 | Screw-set / setting tool | Zinc plated steel | Yes u2014 removable | | M6 | 12 | 5~25 | 45 | 16.0 | Screw-set / setting tool | Zinc plated steel | Yes u2014 removable | Inside the plant ## Manufactured in our own plant This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided. 1. ![Wire rod feeding into a cold heading machine](https://engineeringhardware.com/wp-content/uploads/2026/08/09-wire-rod-feed-cold-heading-machine.webp) 01 **Cold heading** Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail. Head dimensions and under-head radius checked at set-up and per shift. 2. ![Thread rolling machine producing bolt threads](https://engineeringhardware.com/wp-content/uploads/2026/08/03-thread-rolling-machine-bolt-production.webp) 02 **Thread rolling** Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch. Go / no-go ring gauges to ISO 965 tolerance class 6g. 3. ![Baskets of bolts staged for heat treatment](https://engineeringhardware.com/wp-content/uploads/2026/08/05-heat-treatment-baskets-black-bolts.webp) 03 **Heat treatment** Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it. Core hardness and tensile tested per lot to ISO 898-1. 4. ![Zinc plated bolts in a treatment basket](https://engineeringhardware.com/wp-content/uploads/2026/08/23-zinc-plated-bolts-treatment-basket.webp) 04 **Surface treatment** Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list. Coating thickness and neutral salt spray hours to ISO 9227. ## Frequently Asked Questions ### Are Hollow Wall Anchors (Molly Bolts) made to a recognized standard? Yes — they are manufactured to Trade series (metal cavity anchor), so dimensions are interchangeable between suppliers when you quote the standard on your order. ### What are Hollow Wall Anchors (Molly Bolts) used for? Fixing steelwork, plant and services to concrete and masonry, where the anchor is set in a drilled hole and its capacity is governed by the base material rather than by the steel. They are supplied to Trade series (metal cavity anchor). ### Which industries use Hollow Wall Anchors (Molly Bolts)? They are commonly specified in maintenance & repair (mro), fabrication & metalwork and structural fixing to concrete, among other sectors. ### How do I choose the right size of Hollow Wall Anchors (Molly Bolts)? Match the nominal size to the mating thread or hole. This product is available from M4 to M6; the full dimension table on this page lists each size. ### Can I get a quote for Hollow Wall Anchors (Molly Bolts) in the size and material I need? Yes. Use the technical drawing and quote form on this page to set the size and options, then send the exact configuration to our team for pricing and lead time. ## Related Pages Product page: [Hollow Wall Anchors (Molly Bolts) — specifications & sizes](https://engineeringhardware.com/fastener/hollow-wall-anchors/) ### Hollow Wall Anchors (Molly Bolts) Specification Guides ### Related Fastener Applications