Metallics J3124 Anchors 5/16 X 2-1/2 Slv Ancr &Nt St-zn (Jar 100)

The Metallics J3124 is a 5/16 x 2-1/2 inch sleeve anchor supplied with its nut. Sleeve anchors are drilled to the same diameter as the anchor, so a 5/16 inch carbide bit in concrete, block, or brick, drilled deeper than the 2-1/2 inch anchor length so the dust has somewhere to go. The expanding sleeve lets it hold in hollow block as well as solid concrete, which is why electricians reach for it over a wedge anchor on CMU walls.

A sleeve anchor like the 5/16 x 2-1/2 J3124 works in hollow concrete block, brick, and solid concrete because the sleeve expands against the inside of the hole as the nut is drawn up. Where there is no masonry at all, drywall or plaster over a cavity, a sleeve anchor is the wrong part and you want a toggle or a self-drilling drywall anchor.

Total anchor length is 2-1/2 inches, and that length is split between embedment in the base material and the thickness of whatever you are fastening. Keep enough of the sleeve in the concrete to expand fully, so plan on roughly an inch or so of grip for the bracket, strut, or panel flange. For thicker standoffs or layered material you want a longer anchor in the same 5/16 diameter.

Steel with a zinc plating, which is the standard finish for dry interior and protected exterior work: strut runs, panel and disconnect mounting, conduit standoffs. It is not stainless, so for direct weather exposure, wash-down areas, or coastal and chemical environments specify a stainless anchor instead.

100 pieces per jar, nuts included, so you are buying the complete fastener and not sourcing hardware separately. The jar pack is sized for a van stock or shop shelf rather than a single install, which suits contractors standardizing one anchor size across a building.

Order it as Metallics J3124. That number covers the 5/16 x 2-1/2 inch zinc plated steel sleeve anchor with nut in the 100 piece jar, which is the designation to quote if you are matching anchors already installed on a site.