Bunk bracket sandwich plate.For added strength to standard flat bunk brackets.Helps keep brackets locked into set positions.Made of pre-galvanized steel.Fits 2" high tube crossbars.Mount between face of bunk bracket and 1/2"Dia nut.Covers the slots to give the nut a solid surface to lock onto.Helps prevent brackets and u-bolt from kicking out under heavy loads.Sold as each