The DIY solution that stops water surge pipe banging caused by quick-closing valves. A patented triple O-ring sealed air chamber, maintaining a 60 PSI air charge absorbs the high-pressure surge. 1 per card with installation instructions. Female hose x Male hose to install in supply line for washing machines. Oatey Water Hammer Arrestors model No. 38601 and 38600 both meet the ASSE1010 standards that are acceptable for the state of Wisconsin.