BrassCraft 1/2 In. Nom Compression Inlet x 3/8 In. OD Compression Outlet 1/4-Turn Angle Ball Valve features lockshield and a loose key to help prevent tampering and accidental activation of water flow. Used to control water flow to household plumbing fixtures, this angle valve is most often used where the water pipe enters the room from the wall. With a quarter turn of the loose key, you are able to start or stop the flow of water leading to the plumbing fixture, allowing for maintenance and repair without shutting off the water to the entire home.