U-Bolt Square U-Bolts SQUARE U-Bolts Grade 8 Square U-Bolts Measure the diameter of the rod and click on the link below to purchase the appropriate Grade 8 Square u-bolts we stock.Each kit includes two u-bolts, washers and nuts. Square - 5/8" U-Bolt Square - 3/4" U-Bolt Square - 7/8" U-Bolt Square - 1" and larger U-Bolts