Oatey® 39177 Quiet Pipes Male Iron Pipe Shock Absorber, 1/2"Designed to reduce water pipe banging noise caused by quick closing valves and protect plumbing appliances and fixtures from the effects of water hammer. Quiet pipes absorbers contain a piston that uses a triple o ring to maintain 60 PSI charge in the tube. When the water valve is shutoff, it sends a shock through the system and the piston compresses. This absorbs a shock that would normally rattle and shake the pipes. 1 2" Male iron pipe Material: