Molly Bolts vs. Sleeve Anchors
Comparing 2 standards across 12 specifications. 12 key differences identified.
The Hollow Wall Anchor (Molly Bolt, patented by George F. Croessant in 1934) is an all-metal expansion fastener featuring a slotted steel sleeve that permanently crimps into 4 outward-flaring legs behind hollow drywall or plaster. Unlike toggle bolts, the anchor sleeve remains permanently clamped to the wall, allowing the machine screw to be removed and re-inserted repeatedly.
The Concrete Sleeve Anchor (Dynabolt) is a versatile medium-to-heavy duty masonry anchor comprising an internal threaded bolt, a flared cone mandrel tip, and a full-length tubular expanding metal sleeve. As the bolt or nut is tightened, the cone is pulled into the sleeve, expanding it along its full length to grip securely in solid concrete, solid brick, hollow block, and stone.
Specification Comparison Table
12 Parameters| Parameter / Spec | ||
|---|---|---|
|
Sleeve Material
|
Pre-slotted zinc-plated cold rolled steel sleeve with barbed anti-spin collar | — |
|
Internal Machine Screw Thread
|
M4, M5, M6 (Metric) or 1/8", 3/16", 1/4" (Imperial) | — |
|
Grip Range Sizing
|
Short (1/8" to 3/8" wall thickness), Medium (3/8" to 1/2" drywall), Long (5/8" to 1" double-drywall/lath) | — |
|
Permanent Retention
|
Yes (Sleeve stays permanently crimped into the wall when screw is removed) | — |
|
Setting Method
|
Tightening the screw with a screwdriver or using a specialized manual Molly setting plier tool | — |
|
Safe Shear Load (1/2" Drywall)
|
Up to 50 lbs (23 kg) shear per anchor | — |
|
Standard Specifications
|
— | ASTM E488 / Federal Spec FF-S-325 Group II |
|
Sleeve Geometry
|
— | Full-length cylindrical zinc-plated steel sleeve with pre-cut expansion slits at bottom |
|
Head Style Variants
|
— | Hex Nut, Acorn Cap Nut, Flat Countersunk (Phillips/Torx), or Round Head |
|
Substrate Versatility
|
— | Solid concrete, clay brick, mortar-filled CMU, hollow concrete block, stone |
|
Drill Bit Size Match
|
— | Borehole diameter matches anchor outer sleeve diameter exactly |
|
Primary Applications
|
— | Door/window security grilles, garage door tracks, handrails, electrical conduit brackets |