This is a side mounted, top hung wardrobe roller assembly with a single 3/4 in. convex nylon wheel for the front sliding door. The stamped steel bracket assembly is adjustable and has an 1/4 in. offset. It is used on 3/4 in. to 1-3/8 in. thick doors and up to 50 lbs. maximum each. Used by Cox door systems as well as a variety of other wardrobe door manufacturers. For the back wardrobe door se Prime-line part N 6509.