The SharkBite water hammer arrestors are the fastest and easiest way to reduce or eliminate water hammer. These fittings are designed for a maintenance-free protection system against the sudden stoppage of water flow in your water distribution system. This sudden stoppage sometimes results in a loud knocking noise. This product is the perfect solution to help reduce pipe noise. They can be easily rotated after assembly and are certified for use as a manufactured joint in underground and behind-the-wall applications without access panels.