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