This is a "C" tab patio door roller assembly with a 1-1/8 in. Dia concave or grooved, steel ball bearing roller. As the "C" shaped tab fits around the corner screw, it is captured by the side stile and bottom rail as the screw draws the two sides together. The housing is 23/32 in. wide and 1-3/16 in. tall with a dimple width of 7/8 in. and most often used by Solar Industries and a variety of other patio door manufacturers.