Superior Parts DBM83-04CQ Carbide Driver, Bumper, Ribbon Spring, O-Ring & High Quality Gasket Service Kit for Hitachi NR83A / A2 which includes SP 877-317 Cylinder Ring, SP 877-334Q Premium Gasket (A), SP 877-325Q Premium Gasket (B), SP 878-421 Ribben Spring Set, SP 878-303 Piston Bumper and SP 877-323C Piston Driver (Japanese Carbide).