12mm Single Check Valve. Non Return valve for 12mm push fit pipe. These fittings are designed for hot or cold water systems in touring caravans. The pipe is simply pushed into the fitting to form a safe secure connection. The body is produced in acetal copolymer. O Rings are nitrile rubber. The collet is produced in acetal copolymer with stainless steel teeth. Minimum Working Temperature -20c. Maximum Working Temperature +70c.