Tandem roller assembly used by several patio door manufacturers of metal or vinyl framed patio doors

It has an in-line tandem inner housing with 1-1/4 inch concave or grooved steel ball bearing rollers set in a stamped steel housing with rear adjustment

The housing is 1-1/32 inches tall, 11/16 inches wide and 3-1/8 inches long with a 1/4-20 threaded mounting hole on the back end and and optional use hole on top