Concrete Sleeve Anchor (Dynabolt)
Direct Answer
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.
Source: ASTM E488 / Federal Specification FF-S-325
Specs
| 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 |
Full-Length Sleeve Compression
Unlike wedge anchors that only expand a narrow clip ring at the deepest tip, a sleeve anchor's full-length metal tube distributes expansion force along the entire buried depth of the hole. This lower, distributed radial pressure allows sleeve anchors to achieve dependable holding power in weaker or porous substrates (such as cinder block walls and vintage solid brick) without cracking the masonry face.
Multiple Head Styles for Architectural Finishes
Sleeve anchors are manufactured in four distinct head configurations: external hex nuts for structural framing, decorative chrome acorn cap nuts for exposed railings, flat countersunk heads for flush door thresholds, and round heads for window security bars.