. Hex Head Sleeve Anchors 15-Pack are designed for fastening into porous concrete, hollow or grout-filled block and brick. Dia head x 3 in.Red Head 3/8 in.
This jams the end of the bolt, and provides the strength.Tightening the bolt results in a wedge being driven up against a sleeve. Trubolt Wedge Anchor, 5-1/2" L, Stainless Steel 5 PK.