John Guest� Reverse Osmosis Tank Valve with 3/8" quick-connect fitting This Valve is designed for use with a Reverse Osmosis Bladder Tank. These valves are manufactured in white polypropylene with food grade EPDM 'O' Rings for use with potable water. The valves are not to be used with compressed air, explosive gases, petroleum spirits and other fuels or for heating systems. This fitting is made of the following components: The body is produced in polypropylene 'O'Rings are EPDM The collet is produced in polypropylene with stainless steel teeth The handle is produced in acetal copolymer This valve is NSF Certified