All Balls U-joints are cold-forged from SCM-415 steel with HRC58-61 case-hardened and precision-ground journals for extra fortitude. The bearing cups feature a quad lip seal and centrally located grease Zerk and channels to evenly distribute grease and keep contaminants out. The U-joints are pre-greased with high-temperature Lithium Complex 3 grease—and a cap plug is included to eliminate grease Zerk in low-clearance applications. Replace the old, with the new high-quality All Balls Racing U-joint kits.