This is a side mounted, top hung wardrobe roller assembly with a single 3/4 in. convex nylon wheel for the back sliding door. The stamped steel bracket assembly is adjustable and has an 1/2 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 many other wardrobe door manufacturers. For the front wardrobe door use Prime-line part N 6508.