Spitfire Formula Four Diameter: 54mm Hardness: 99A Color: 2 blue w/lime graphic, 2 lime w/blue graphic FORMULA 4 Unbeatable lasting performance SPITFIRE urethane. Fast as hell. Long lasting, abrasion resistance, smooth anti-stick slide with a controllable grip. Guaranteed. CONICAL FULL (SHAPE) A wider version of the Conical Shape. Wide riding surface, cut in sidewalls to decrease weight. A solid, Controllable shape for all terrains.