1.various kind of rubber, such as Viton,HNBR,EPDM,silicone,Neoprene. 2.use in variuos of field, auto,machine O Ring sealing is one of our specialties,and we can make any type any color o ring sealing products. The hardness and the tensile strength is well tested in our experimental room before we start to have mass productions. We only need you sample or even your drawing, they we can have our ...