Aqua Plumb 1115 3 In 1 Combo Inline Sump Pump Check Valve 1-1/4" IPS OR 1-1/2" Copper or 1-1/2" IPS, For 1-1/4" Or 1-1/2" Lines Installation, Includes 2 Rubber Reducing Sleeves & 4 Stainless Steel Clamps, Ready To Install On 1-1/2" Discharge Pipe, Reverse Reducer Sleeves For Use On 1-1/4" Discharge Pipe. HBC check valves allow for the unrestricted flow of water up and out through the pipes, but when the pump turns off, the water in the pipes doesn’t flow backwards back into the sump pit causing more work and wear on the sump pump.