The Smith adjustable Swivel Bracket Assembly is designed to support roller bunks. Hot dip galvanizing provides years of use in the harsh marine environment. Swivel bracket enables bunk to tilt when loading a boat. Mounting slots allow for height adjustment. Dimpled surface keeps bracket from sliding along trailer frame. Bolster and swivel bracket assemblies are typically mounted upright on the boat trailer cross members. They allow a mounted roller bunk, which is run from the front of the trailer to the back, to pivot while you are loading a boat.• 11-gauge galvanized steel• Overall Assembly: 11"L• Made in the USABolster Bracket:• 2-1/2"W x 10"L• Slots: 1/2"W x 3-3/4"L• Distance Between Slots: 1/2"• Swivel Hole: 1/2" dia. Swivel Bracket:• 1-3/4"W x 2"L• Top Flange: 1-1/4"• Top Flange Hole: 7/16" dia. Mounting slots for height adjustment Galvanized steel construction 11"L overall assembly | Roller Bunk Swivel Bracket Assembly Made in USA