Air Craft grade aluminum extruded/ machined hub. Oversized shape and low profile tire provides a superior feel and maximizes your roll. Tire chemically bonded to the core to prevent any delimitation or shifting of the tire giving you a more responsive and reliable wheel. Tire made from a proprietary formulation that is developed in house at the RollerBones factory in Santa Barbara, California, USA. High rebound, abrasion resistant urethane makes for the fastest and longest lasting wheel