The Blaster Formula AIR-Tech Wheel has two layers of material to optimize performance. An 88A durometer outer urethane provides faster speeds, slower wear, and superior flat-spot resistance. This compound is preferred by advanced riders seeking an ultra-responsive wheel. The softer Adaptive Inner Ring (AIR-Tech) increases grip, durability, and impact absorption. The molded Bond-Guard urethane shape helps reduce sideways impact damage and keeps the hub-to-urethane bond strong.