A plumbing piece is an essential component of a plumbing system. An ELBOW (ELBOW) is a curved PIPE fitting that is used to change the direction of the flow of water. A TEE (TEE) is a type of fitting that has three openings and is used to connect two pipes at a 90-degree angle. An ELL (ELL) is a type of fitting that has two openings and is used to connect two pipes at a 45-degree angle. Finally, a PIPE (PIPE) is a hollow cylinder used to transport liquids or gases.