Superlift Suspension U-Bolts are manufactured from low alloy, high strength steel. U-Bolts up to 13" long has a typical yield strength of 90,000 PSI and a tensile strength of 120,000 PSI. The 14" and longer U-bolts typically have a yield strength of 115,000 PSI and 133,000 PSI tensile strength. Thread type is National Fine Class 2A. U-bolts come in either anti-corrosion zinc or black e-coat finish.Superlift U-Bolts are sold in 4-packs and come with paired, aircraft type Nylon inserted locking nuts and phosphate coated, heat treated extra thick washers.