... platingSeat Material:natural rubber,butyronitrile tubber,neoprene and ethylene-propylene rubber,hypalon,silicone rubber, fluororubber,ptfeSurface Treatment ... ,aluminium alloy materials,aluminium bronze. Seat selects different rubber material with chemical and physical properties, high-performance ... the product. the operating torque belows normal butterfly valve,and easy maintenance,working life is five ...