Maximize flow from your sump pump with this PumpSpy check valve. It stops water remaining in the sump discharge pipe from falling back into the sump pit. This avoids pumping the same water twice, extending the life of your pump. A clear valve body allows visible water movement to make it easier to verify that your sump is flowing properly. To minimize the water hammer noise of a standard check valve, it offers a spring-loaded flapper. Sturdy ABS construction ensures lasting use.