Prime-Line N 6599 Mirror Door Roller Assembly, 1-1/2 in., Plastic Wheel, Ball Bearings, Concave Used by Monarch Door Company on "500" series aluminum-framed sliding mirror closet doors 1-1/2 in. outside diameter wheel in 1-3/4 in. x 1/2 in. x 3 in. assembly housing Concave edge wheel (center grooved) Constructed of a plastic wheel with steel ball bearings, assembled in an extruded aluminum housing