... can supply 25#, 30#, 35# and 40# silicone valve core seals 2) High quality Features:1) Available material: materials ... FKM), viton DuPont & Dow elastomers, neoprene, HNBR, NBR + PVC, natural rubber, SBR, IR, IIR (butylrubber), CR (neoprene), SBR, AU, ACM, ... mold support and samples 6) Customer's design and specifications are accepted 7) Available in various sizes and colors Rubber silicone valve core ...