The 4 in. Wye Fitting attaches two pc. of pipe at a 45 degree angle. The is designed to split runs of 4 in. single-wall corrugated polyethylene drainage pipe. All you have to do is snap Wye fitting onto on piece of pipe, then attach second piece of pipe by easily snapping it into the opening in fitting. Made of durable, high-density polyethylene construction, the Wye fitting is both corrosion- and abrasion-resistant.