Bonded Seal Washers: These washers are used to seal bolt heads and prevent leakage from hydraulic fittings, pipe joints and valve bodies. A bonded washer consists of a metal washer bonded to a rubber internal diameter that is wider than the washer. As the bolt is tightened, the rubber seal element is compressed until the bolt head contacts with the metal outer of the washer, creating an efficient high-pressure seal. The inside material will be made from Nitrile Rubber. EPDM, Silicone, and Viton are available upon request.