This patio door roller is constructed from steel

Back patio door roller assembly with a 1-1/2 inch concave or grooved steel ball bearing roller

It has a plain back housing that is 11/16 inches wide, 1-1/4 inches tall and 2-3/8 inches 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 comes affixed to an adjustable steel housing assembly

This style roller is used by Lenahan and other glass door manufacturers