Features The bottom valve, also called a check valve, is a low-pressure flat valve. The purpose of the pump is to ensure that the liquid in the suction line flows in one direction so that the pump can work properly. If the pump stops working intermittently, the liquid cannot be returned to the water source tank and the suction pipe will be filled with liquid to make it easier to start the pump. Uses high quality PVC material that can withstand long working in water. Professionally and practically designed with good work performance. Features: The bottom valve, also called a check valve, is a low-pressure flat valve. The purpose of the pump is to ensure that the liquid in the suction line flows in one direction so that the pump works properly. If the pump stops working intermittently, the liquid cannot be returned to the water source tank and the suction pipe will be filled with liquid to make it easier to start the pump. Uses high quality PVC material that can withstand long working in water. Professionally and practically designed with good work performance. Specification: Item Type: Pump Foot Valve Material: PVC Color: Black Type: 1.5 inch 2 inch 2.5 inch 3 inch 4 inch (Optional) Package list: 1x valve Package List