... : 1) We can supply 25#, 30#, 35# and 40# silicone valve core seals 2) High quality Features:1) Available material: materials for ... DuPont & Dow elastomers, neoprene, HNBR, NBR + PVC, natural rubber, SBR, IR, IIR (butyl rubber), CR (neoprene), SBR, AU, ACM, CO, etc. NSF ... ) Available in various sizes and colorsInner packing:500pcs/bag Silicone Valve Cores