Magic Plastics - Inline Check Valve, 1-1/2in Slip Socket, PVC, 0821-15

Magic Plastics Inline pool and spa plumbing water check valve, 1.5"" slip socket with a 1/2 lb internal spring, Magic # 0821-15. Used to prevent cycling or backflow of water within a 1.5"" pipe. Installs in one direction only, to keep water moving in one direction only. Often used in front of the pump or heater, or before a chlorinator, to prevent back draining when the system is off.