This is a unique tandem roller assembly with two 1-1/4 inch concave steel ball bearing rollers installed. The square shaped housing is 11/16 inch wide, 1-1/2 inch tall, and 4-1/2 inch long. It has an end adjustment screw and two mounting tabs at each end of the housing. When the housing is inserted into the mortised area in the bottom rail, screws are used to fasten it in place.
This patio door roller is constructed from steel and has tandem rollers with a diameter of 1-1/4 in. It comes affixed to an adjustable steel housing assembly. This roller is used on vinyl or wood patio doors.