For 3/4" to 1-3/4" thick doors 24" to 36" wide up to 6'8" high and weighing up to 125 lb. To be used for standard 3-1/2" (2 x 4) stud walls. Easy-to-install, 4 wheel hangers for smooth long-lasting operation. Extra-strong, steel studs for a solid wall. Preassembled header system with aluminum rail. Rough opening: Width is twice door plus 1"; height is door plus 3-3/4"; plus finished floor.