Rare Parts RP12573 Ball Joint Kit PATENT-PENDING adjustable load carrying cap sets load distribution Upper Ball Joint, USA-made tapered roller bearing carries axial and radial loads Upper Ball Joint, Polyurethane wipe seal prevents contamination - mounted internally to prevent tearing and friction between knuckle and ball joint face Lower Ball Joint, HEXAD Grease System - 6 equally spaced grease grooves evenly distributes grease; With every turn of the wheel, grease is spread in between the two wear surfaces 32MM powdered metal bearing replaces the undersized OE plastic bearing, increasing load carrying capacity