a plastic tee fitting formed by a main conduit body and an internally threaded adapter connected to the body at a right angle . the adapter is arranged end to end with a hollow neck which projects from the wall of the main body around a circular opening in the wall . the joint between the neck and adapter is strenghtened by an insert which is fitted in and glued to the neck and adapter on the inside and by a spout which is sleeved around and glued to the neck and adapter on the outside .