Engineered for strength, durability, and simplicity. Made of hot-dipped galvanized steel. Stationary dock hardware is designed with 7/16" holes for 3/8" carriage bolts. Prevents pipe from deforming wood so that the dock slides down the leg pipe. Also prevents bolts from working into the wood and lock washers from working loose. Measures 5-1/4"L x 5-1/4"H. 5-1/4"L x 5-1/4"H | Stationary Dock Hardware Backer Plate