This is a plain back, patio door roller assembly with a 1-1/2 in. concave, or grooved, steel ball bearing roller. It has a plain back housing that is 3/4 in. wide with a 13/16 in. dimple width, and 1-5/8 in. tall. It is rear adjusting with a 1/4-20 threaded mounting hole on the back end. It is used by Keller and a variety of other sliding patio door manufacturers.