Compatible with most reverse osmosis systems (including brand names) in the market. - to be installed on the outlet port of membrane housing where pure water exits. - quick connect union check valve features 1/4 inch quick connect fitting with plastic insert check vale. - prevents the flow of water back in to the ro membrane. Why ispringlocated in Alpharetta, Georgia for over a decade, iSpring water systems LLC is a family owned company specializing in reverse osmosis water filtration systems. Our products include residential and commercial reverse osmosis (ro) systems, whole house water systems, Ultrafiltration systems, shower, faucet, and counter top filters, filter cartridges and housings, ro coolers, and kitchen faucets and fittings. Our aim is to make high quality drinking water accessible for all households. With affordable pricing, solid quality, Prompt delivery, and top notch customer service, we hope to assist in bringing you great water for years to come.