This is a F-tab patio door roller assembly with a 1-1/4 in. concave steel ball bearing roller. When the corner screw passes through the F-tab it is captured by the side stile and bottom rail as the screw draws the two sides together. The housing is 9/16 in. wide with a flare width of 11/16 in., 1-1/8 in. tall and 1-1/4 in. long (not including the inner roller housing). It has a rear adjusting screw. Used by a variety of patio door manufacturers.