39.6"/3.3FT Rail Hardware Bi-Folding Sliding Barn Door Hardware Track Kit Heavy Duty Aluminium Alloy Wall Mount Kit for 2 Doors (No Door)Reference Dimension 39. 6" bi folding box rail kit fit Max door opening width 35" (890mm); Width of each door=1 2 (door opening width + 4"); The minimum distance from the top of the door to the ceiling is 4. 75"(120mm); Fit door thickness 1. 18 1. 77 (30 45mm). Heavy Upgraded & Heavy DutyUpgraded aluminum alloy box track and nylon roller, box rail hanger bearings for barn door up to 330 lbs(150kg). Whether for Interior or exterior use, the bi fold