PVC 20mm Grey 90° Elbow fitting is a type of plumbing fitting used to connect two pipes at a 90-degree angle. The "PVC" refers to the type of plastic the fitting is made of, which is known for its durability, resistance to chemicals, and low cost. "20mm" refers to the size of the fitting, which is the inside diameter of the pipe it will fit on. The "Grey" is the color of the fitting, this color code is use to identity the material and also indicate the pressure rating of the pipe fitting. The "90°" refers to the angle of the fitting, this allows you to change the direction of the pipe at 90-degree angles. This type of elbow fitting is typically used in irrigation, plumbing and pool or spa piping systems to change the direction of the pipe and allows pipes to connect at different angles.