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 11/16 in. wide, 1-1/4 in. tall and 2-3/8 in. long. It is rear adjusting with a 1/4-20 threaded mounting hole on the back end and a #10-32 threaded optional use hole on the top. It is used by Daryl, Lenahan, Patio Magic and a variety of other manufacturers of sliding patio doors.