Fix the knocking noise in your pipes by using the Homewerks Water Hammer Arrestors. The banging sounds in your pipes is caused by sudden stop in the flow of high speed water resulting in an increase in pressure. Water Hammer Arrestors absorb the shock created by the spike in pressure to stop the banging and prevent pipe damage. Homewerks Water Hammer Arrestors are designed for residential use and can be used for up to 3 plumbing fixtures. Various connection sizes and types are offered for your convenience. Features: Copper construction AA size, can be used for 1-3 fixtures Certified lead free and certified to ASSE standards Can be installed on hot and cold water supply lines at any angle or direction CPVC fitting with a sweat connection Max 250 psig Stops banging in pipes and prevents pipe damage