Heavy-Duty Apron Bracket, Sliding Door Box Rail, Max. Weight (Lb.) 600, Material Steel, Bright Zinc Finish, Length (In.) 4-5/8, Height (In.) 8-3/4, Width (In.) 2-3/8, Max. Wheel Dia. (In.) 2-1/8, Ball Bearings, Number of Wheels 4, Construction Steel, Hardware Included, For Use With Doors Weighing Up To 450 Pounds, Includes Hardware, Package Quantity 1.