5" X 1-1/4" Mold-On Rubber Aluminum Swivel Caster, Total-Lock Brake - 375 lbs. Cap.5" x 1 1 4" Rubber on Aluminum Wheel Swivel Caster with Total Lock Brake The mold on rubber aluminum wheel is a lightweight alternative to the traditional cast iron core, providing the same load capacity with a cushioned tread and an attractive look. Tread: Rubber, Vulcanized To Core Core: Aluminum Bearing: Ball Bearing Rig: Zinc Plated Swivel Caster With Swivel Dust Cap, 2 3 8" x 3 5 8" Mounting Plate, Total Lock Brake Capacity: 375 Lbs. Color: Gray