Prime-Line Products N 6861 Mirror Door Roller Assembly, 1-1/2 in., Steel Housing & Ball Bearings, Concave Plastic Wheel Most commonly used on wood framed sliding mirror doors 1-1/2 in. outside diameter wheel Concave edge wheel Constructed of a plastic wheel and an adjustable steel housing Nylon construction Adjustable steel housing Used on wood framed sliding mirror doors Concave ball bearing wheel 1-1/2 in. wheel