This 1/2 inch, unit size A lead free water hammer arrestor is used in commercial and industrial applications to control water pressure shock and prevent water hammer conditions. It consists of a copper body with a lead free brass NPT threaded hex adapter, EPDM seals and O-rings, polypropylene piston, and cap. It is factory air charged at 60 psi (4.2 bar) and is permanently capped and epoxy sealed to absorb the shock and is not rechargeable. It may be installed in new or existing plumbing systems with a standard pipe tee vertically, horizontally or at any angle and is ideal for commercial dishwashers, washing machine, and quick-closing faucets applications. It is designed to operate on all domestic and commercial lines at 150 psi (10.3 bar) working pressure. This water hammer arrestor, size A is used to cover the required PDI listed 1 to 11 fixture units.