HEAVY DUTY CONSTRUCTION? Barn box rails made of solid steel, fine black powder coated surface, anti-corrosion ensures years of beauty and longevity. 8.8 grade screws and roller screws ensure our hardware kit can hold 330lbs doors. Over 15000 times test, bearing rollers slide like butter, slide quiet and smoothly. DOOR WEIGHT CAPACITY? Hold MAX door weight 330lbs, can be used for both interior door and outside door. Suitable for door panel thickness 1 1/2′ to 2′; The rollers vertical lock nuts are adjustable. Fit exterior door and indoor project. SMOOTH BALL BEARINGS SLIDES? All Rollers Equips with 2 Ball Bearings -Bearings provides a very quite and smooth glide as the door opens and closes, smooth every slides. KIND REMINDS? The gap between door and wall is supper small, the box track need install on the wood board. Only box rail barn door hardware for sale, door panel and handle are NOT included.