Hot-Dipped Galvanized Replacement Swivel Top for a Swiveling Bunk Bracket. This Boat Trailer Swivel Angle easily replaces rusted out Swivel Tops on your Trailer Bunk Brackets. These Swivel Top Pieces are designed to mount 2"x4" Bunk Boards and adjust them to the desired angle to better fit the hull of your boat. This Hot-Dipped Galvanized Swivel Top Bunk Bracket is made of 1/8 inch steel (11 gauge), measures 3 1/2 inches on it's longest side and 2 inches tall. The Top holes measure 1 1/4 inches center to center, or 2 1/2 inches center to center between the 2 farthest holes.