Description: Upgraded Design: Our U-bolts feature an extended thread design, suitable for different widths of trailer crossbeams. U-bolt measure 1/2" diameter, 3-1/5" wide, by 4" long, will fit your trailer perfectly. Anti-Corrosion and Anti-Rust: Our swivel top bunk brackets are made of heavy duty galvanized iron, not easy to bend or deform. 10 inches bunk mounting kit is perfect for both freshwater and saltwater boat, pontoon, jet ski trailers. Adjustable Angle: .