Pro Comp U-bolt kits are pakaged complete with new hi-nuts and extra thick washers. U-bolt lengths are usually adequate for stock and aftermarket leaf spring packs. Pro Comp U-Bolt kits are manufactured from low-alloy high strength steel. Round style U-bolts are zinc plated. Square U-bolts are unplated in order to preserve the integrity of the steel at it's bent points. U-bolts are equivalent in strength to a Grade 5 bolt.