Oatey® 38600 Quiet Pipes Washing Machine Supply Line Shock AbsorberDesigned 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. Material: Copper body