Large Vertical Bumper Brackets attach directly to the side of wood or metal docks. Simply added a 4″x 4″ wood post encased in a white fence post sleeve and attach to the brackets. For a stylish and simple look visit your local hardware store and choose from any number of caps for the perfect finish. Vertical bumper brackets are made from marine-grade aluminum and ASTM F 593 Stainless Steel hardware comes with each bracket. Bolts measure 5/16-18″ diameter. Follow the pre-drilled bolt pattern on each side of the bracket when attaching a sleeved 4 x 4 wood post. Manufactured in the USA by Metal Craft Docks