This 4" x 2" flat tread thermoplastic rubber heavy duty rigid caster with tread brake provides smooth and quiet operation. They are safe to use on all floors. Our 45 Series is an economical lineup of casters and wheels designed for a range of applications with load requirements ranging from 300 to 1,250 pounds per caster. From shop carts to containers, to platform and lumber carts the 45 Series is the most competitive and in-stock 2" wide solution.