Spring Check Valve. 1/2 lbs. spring gives positive seal with no back pressure. Reinforced Poppet. Designed for any system where back flow is not desired. Spas, swimming pools, industrial and irrigation. Complies with all applicable ASTM and ANSI standards. UL recognized spa component. PVC Spring Check ValveFPT x FPTPrevents back flow and keeps prime in water systems1/2 pound spring gives positive seal with no back pressure140 Degree F max.150 PSI max working pressure