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. How Sold This item is sold as a set of 5. Thus, selecting a quantity of 1 will result in 1 set of 5 casters being ordered. Selecting a quantity of 3, for example, will result in 3 sets of casters (3 x 5 = 15) or 15 casters being ordered.