This Hot Dipped Galvanized trailer axle U-Bolt Kit is designed to be used with 2 inch Square 2,000 lb capacity axles with slipper springs and mounts diagonally across the axle. You will have one u-bolt per leaf spring on each side mounting diagonally. The leaf spring u bolt kit includes (2) Galvanized 1/2 inch diameter u bolts that are 3 1/16 inch wide inside and 4 5/16 inch long. Also included in this kit are (2) mounting plates and (4) nuts, (4) washers, and (4) lock washers.