... : 1) We can supply 25#, 30#, 35# and 40# silicone valve core seals 2) High quality Features:1) Available material: ... materials for silicone, NBR, fluorosilicone, viton (FKM), viton DuPont & Dow elastomers, neoprene, ... SBR, IR, IIR (butyl rubber), CR (neoprene), SBR, AU, ACM, CO, etc. NSF-61 approved material, meet drinking water system requiremnets ...