Our Brumleve Aluminum Standard Tarp Bow Bracket is designed to keep your steel tarp bows secure inside the trailer while also allowing them to easily slide in and out for quick install and removal without tools. Solid cast aluminum construction. Compatible with Kwik-Lock and Shur-Lok side-to-side roll tarp systems. Mounting plate is 4.00 x 3.50 inch. Inside diameter of socket is 1.00 inch. Mounting screws NOT INCLUDED Please note that we recommend installing ONLY (2) screws when mounting the bracket to your trailer. The reason for this is if the bracket breaks off at some point during its lifetime, the other two holes can be used for re-mounting the bracket in the same location.