Red Head 3/8 in. x 3 in. Zinc-Plated Steel Hex-Nut-Head Sleeve Anchors (50-pack) are designed for fastening applications in porous concrete, hollow or grout-filled block and brick. Use to install hand rails, machinery and supports, window frames, partitions, cabinets and pipe supports. Red Head Sleeve Anchors are contractor grade and building code approved.