Radial Shape – Round edge design for control, speed and a responsive slide.

99d Durometer – Best used in a pool or park with a little more grip than harder wheels, and a little more slide than softer wheels. The right wheel for moderately skilled riders who also want to skate street when needed. Sliding is a breeze thanks to their hardness, while soft enough for a smooth roll and plenty of grip.

Formula Four Urethane – Formula Four urethane is unlike any other. Both in the streets and under high-speed stress tests in Spitfire's lab, Formula Four wheels retained more material, coned less and kept their original shapes and sizes longer than any other wheel.