Simpson Strong-Tie® mechanical anchors are designed to install easily and securely into a variety of base materials, including concrete, grouted or hollow CMU and brick. Specifiers and contractors trust Simpson Strong-Tie anchors for optimum performance under the most demanding structural applications. The Split Drive anchor is a one-piece anchor, with a split-type expansion mechanism on the working end. As the anchor is driven into the hole, the expansion mechanism compresses and exerts force against the walls of the hole. CSD 1/4 in. x 3-1/2 in. Zinc-Plated Split-Drive Anchors (100-Qty) (Pack of 400).