This is a C-tab patio door roller assembly with a 1-1/4 in. diameter 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 is most often used by Solar Industries and a variety of other patio door manufacturers.