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