... like NBR, HNBR, SI, Viton, FKM, ect.will be available for NSF o-ring Rubber O-Ring1. Offer a wide range of rubber O ... . Various materials and hardness for your option, including Buna-N (NBR), HNBR, VITON, Silicone, FluoroSilicone, EPDM, Teflon, Natural Rubber, BUTYL, SBR, Neoprene, HYPALON ...