These caster series all feature Hamilton's new UltraGlide®; wheels. Like its twin-wheel predecessor, these wheels feature independent swivel surfaces that eliminates scrubbing, making it much easier to turn. The wheels also have the prior wheel’s split outer raceways to minimize friction that provides low startup and maintain forces. That’s where the similarity ends. Engineers upgraded the precision ball bearings in both size and quality in the new UltraGlide® to provide more than double the bearing life. Hamilton engineers also designed the die cast aluminum center with a new concave face that concentrates the compression of the urethane toward the centerline of the tread. This design change simulates the cushioning benefits of a thicker, softer tread, but provides the same durability and long life as other more conventional heavy duty wheels. The UltraGlide® also features a new modular design whereby the 1” wide wheels are no longer press fit together but now assembled separately like a true multi-wheel arrangement. This enhancement allows for many more product configurations compared to its predecessor. For example, the new UltraGlide® supports a 3” wide assembly in a small 3-1/2” diameter and can expand to a 6” wide assembly in a 12” diameter. The UltraGlide® assemblies are offered in (3) different polyurethane types and two tread profiles. The tread profiles are flat and a new crown profile that features a new and unique easy rolling flat center band.