O-Ring Rebuild Kit is for PGD2000 and PGD2000X post drivers. Inncludes Viton O-rings for the hammer and anvil, O-rings for the damper assembly, housing O-ring seal, and EP 0 grease. The post driver works by simply moving compressed air. We recommend replacing all O-rings annually or if you notice inadequate performance. Replacing these O-rings will restore the compression and performance of your driver. Includes O-ring 76×2.65 Nitrile, O-ring 37.5×3.5 Viton (pack of 2), O-ring 40×5.3 Viton (pack of 2), O-ring 45×3.5 Viton, O-ring 56×2.65 Nitrile, Titan EP 0 grease (4 oz).