BSW1009 Features: * Check valve * Material: Plastic * Installed on sump pump discharge pipes to keep water from returning to the sump pit when the pump stops * Keeps flooding water from entering the building through the discharge pipe * When the pump is running the flapper in the check valve opens and lets the water out * When the pump stops, the water above the check valve rushes back down and automatically slams the flapper closed * While this keeps the water from reentering the pump pit, it also makes a loud and annoying clunking noise * Large silencing air chamber that absorbs the sound of the returning water and reduces the noise when the pump stops * Won"t be awakened on rainy nights by a clunking noise every time the sump pump stops * Eliminates the irritating "clunk" that can happen when your sump pump turns off * Patented silencing air chamber design absorbs the shock that normally happens after pump shut off * Easily install on both 1.5"" and 1.25"" pipes with no gluing required * Fits easily in compact spaces * Air tight chamber prevents water entry * Not for use with ejector pumps Includes: * Stainless steel hose clamps included Color/Finish: * Color: Black Dimensions: * Dimensions: 12"" H x 5"" W x 3"" D