Designed for maximum flow from your sump pump. ProCheck full-flow check valves prevent remaining water left in the sump discharge pipe from falling back into the sump pit. Features clear valve body so that water movement is visible, making it easier to verify that your sump is flowing properly, and the valve is seating when closed. The unique spring-loaded flapper eliminates the loud water hammer noise of standard check valves. Durable ABS construction for years of service and reliability. Fernco ProFlex Specialty Couplings connect the check valve in-line with 1-1/2” sump pump discharge pipes and creates an extra-secure pipe connection, engineered with no-rust stainless shields, clamps and bands.