Grex Driver Kit P635KB2 Replacement parts that fit Grex P635 This kit contains Cylinder Cap O-Ring, piston driver Assembly, piston o-ring, mini o-ring, Rear Exhaust seal P6 Series 23 Gauge Headless Pinners are designed for longevity and optimal performance Over time, drivers do fatigue and require replacement. GREX provides support for its P6 Series with Maintenance Kits Detailed instructions are included making it easy to maintain your pinner, Driver Kits include: 96649 Cyclinder Cap O-ring, 64503 Piston Driver Assembly, 96603 Piston O-ring, 96650 Mini O-ring, 63505 Small Exhaust Seal