This metal rubber washer is made of high quality zinc-plated steel. It has an inner ring made of rubber. It acts as a sealing gasket for hydraulic and pneumatic systems. This washer consists of a zinc-plated steel outer side (AISI 1008-1010) and a trapezoidal section gasket, in its inner side, made of NBR. To ensure a perfect sealing, make sure that the temperature is between -30 and 110 degrees centigrade. It is suitable to use on screw heads, pipe fittings, plugs, swivel fittings and acorn nuts. Available in different sizes.