... ROHS approved 3.100% factory sales&tested O-Rings 1. Offer a wide range of o-ring in all standard size and a ... lot of special size. 2. All o-rings are made according to international standard: ISO 3601, AS 568A ... hardness for your option, including Buna-N (NBR), HNBR, VITON, Silicone, FluoroSilicone, EPDM, Teflon, Natural Rubber, BUTYL, SBR, Neoprene, HYPALON, etc ...