... viton DuPont & Dow elastomers, neoprene, HNBR, NBR + PVC, natural rubber, SBR, IR, IIR (butylrubber), CR (neoprene), SBR, AU, ... etc. NSF-61 approved material, meet drinking water system requiremnets 2) All manufacturing processes confirm to the ... ISO-9001, ISO14001 and NSF-61 system standards 3) Excellent chemical and physical property4) ... in various sizes and colors Rubber silicone valve core