Concrete Sleeve Anchors' design allows them to anchor into concrete, brick, and block. Turning the nut pulls the working end of the sleeve anchor up through the sleeve, expanding and anchoring itself securely in the base material. Hillman 1/2 in. Dia. x 2-1/4 in. L Steel Hex Head Sleeve Anchors come in packs of 15, handy for types of applications.