For doors 1-1/8" to 1-3/4" thick, up to 3' 0" wide and weighing up to 100 pounds. Zinc finished, 0.030" gauge galvanized steel track is jump-proof box style with V-shaped rails. Hangers have four 7/8" diameter lubricated Celcon wheels. . Conforms to ANSI A1 56.14/Type : D8691.