Prime-Line Products N 6529 Prime Line Flat Edge Door Roller Assembly, 1 in Dia X 1/4 in W, Nylon, 1&quot, Mill Adjustable bracket Twin wheels 1 inch O.D. Flat edge nylon wheel fits 3/4 inch to 1-3/8 inch thick doors 5/16in.-18 threaded shaft This tandem roller features 2 flat edged nylon wheels affixed to an adjustable top mounted bracket