1The bottom valve, also known as the check valve, is a low-pressure flat valve. 2The pump is to ensure that the fluid flows in one direction in the suction line, allowing the pump to work properly. 3When the pump stops working intermittently, the fluid cannot be returned to the water tank source, and the suction pipe is filled with fluid to facilitate the start of the pump. 4Uses high-quality PVC material that can withstand long-term work in water. 5Professionally and practically designed with good working performance. Features: The bottom valve, also known as the check valve, is a low-pressure flat valve. The pump is to ensure that the fluid flows in one direction in the suction line, allowing the pump to work properly. When the pump stops working intermittently, the fluid cannot be returned to the water tank source, and the suction pipe is filled with fluid to facilitate the start of the pump. Uses high-quality PVC material that can withstand long-term work in water. Professionally and practically designed with good working 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