All standard models have either an on/off Valve (3/16 Nickel-plated Brass hose barb) or a silicone septum in polypropylene housing; dual-valve models have both. Max Temp: 160°f (71°c). individually sealed in a dust-protected outer bag that also blocks out sunlight. Standard Kynar bags single-wide seam; available in 2-mil and 4-mil thick styles. Dual-valve Kynar bags double-wide streamed bags have both on/off and septum valves for convenient mixing. Dual-valve Kynar bags double-wide streamed bags have both on/off and septum valves for convenient mixing. Corrosive-resistant Kynar for all your application needs strong seams for added durability