90 Degree Elbow Pipe Fitting 4 in. attaches 2 pc. of single wall corrugated polyethylene drainage pipe end-to-end, at a 90 degree angle. Made from durable high density polyethylene, the elbow pipe snaps on easily, for a fast connection. Just snap the elbow fitting onto the end of first piece of pipe, then attach second piece of pipe by snapping it into other end of the fitting. Made of high-density molded polyethylene construction, the 0490AA90 resists corrosion and abrasion.