Don't reuse your old rusty bolts when installing aftermarket control arms when you can replace them with new ones. This kit includes all new hardware for installing either upper or lower rear control arms in you General Motors vehicle. Supplied is (4) 12 mm 10.9 High grade bolts (equal in strength to American Grade 8), (4) 12 mm Nylon lock nuts and washers. Complete kit is bright zinc plated.