Hanger Kit, Sliding Door Box Rail, Max. Weight (Lb.) 450 lb, Steel, Bright Zinc Finish, Length (In.) 4 19/32 in, Max. Wheel Dia. (In.) 2 1/8 in, Nylon Bearings, Number of Wheels 4, Steel, Hardware Included, For Use With Doors Weighing Up To 450 Pounds