O-Ring Rebuild Kit is for PGD3200, PGD3200X, and PGD3200XPM post drivers. Includes 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 42.5×3.8 Viton (pack of 2), O-ring 44×5.3 Viton (pack of 2), O-ring 78×3.8 Viton, O-ring 92×2.65 Nitrile, Titan Ep 0 Grease (4 oz)