D 1603 is an unique back die-cast patio door roller assembly with a 1-1/4 in concave steel ball bearing roller used on crossly doors. It's unique die-cast housing is 11/16 in stepping down to 9/16 in wide, 1-1/8 in tall and 2-5/16 in long with a flare width of 3/4 in. The 9/16 in wide rear design of the housing fits into the door rail held in place by a screw that engages the mounting hole in the back end. The adjustment screw is just above the mounting hole.