Watts Model LF15M2-B 3/4" Lead-Free Water Hammer Arrestor, To Get Rid Of Banging Noise In The Pipes Straight water hammer arrestor Install on any new roughing or retrofit installation with 3/4-Inch FIP fittings 3/4-Inch male iron pipe connection,gets rid of banging noise in the pipes The sealed chamber prevents the loss of air to the water and ensures long and trouble-free life ASSE and ANSI approved, PDI certified, and IAPMO listed. Maximum Working Pressure: 150 psi (10.6 bar)