1、Application: The galvanized swivel bunk bracket kit with the flat surface is suitable for your boat's and trailer's 3in x3in cross members. 2、Purpose: This kit is put together to be ready to assemble on your trailer cross members and secure your bunk boards to the swiveling tops. 3、Adjustable Height: Swivel bunk bracket is 8in height, with slotted holes for multiple height adjustments, better meet your needs. 4、Complete Kit: This kit contains everything you need to mount bunk boards (not included) to your trailer. Perfect for ski boat, fishing boat or sailboat. 5、Including Mounting U Bolts: The included U bolts fit around a 3 inch wide by 3 inch tall cross member, and measures 1/2in diameter, 3in wide, 4 5/16in long.