1-1/2" Swing Check Valve - Slip
Swing Check Valves are mechanical valves that permit water to flow in only one direction. Water flow in the desired direction opens the valve, while backflow forces the valve closed. Install these near your skimmer or filter, so when the pump is turned off for maintenance, water will not drain back into skimmer.
Also used to help external pumps maintain their prime when installed on the suction side of the pump.
Swing check valves are designed for horizontal installations, but may be installed vertically in up-flow only position. Check valves MUST be installed with the valve's FLOW arrow pointing in the direction of the flow. Do not install valve upside down.