Dual Wheels Each of the dual wheels is 2" in diameter and 3/4" in width. Construction The caster body is a composite plastic. The caster tread is thermoplastic rubber and the caster core is polypropylene plastic. The caster axle is steel as is the 360 degree swiveling grip ring stem with brass band. Brake Equipped Two of the casters per set are brake equipped. Weight Capacity Each caster can support 150 lbs. Four casters together could support up to 4 x 150 lbs. = 600 lbs. How Sold Casters are sold as a set of 4. Thus, selecting a quantity of 1 will result in 1 set of 4 casters being ordered. Selecting a quantity of 3, for example, will result in 3 sets of 4 casters or 12 casters being ordered.