Spitfire Formula Four Conical Full 101A. Formulated for a harder, faster ride. Unmatched flatspot resistance. Smooth anti-stick slide. More speed and control. 100% true performance urethane. A wider version of the conical shape. Wide riding surface. Cut in sidewalls to decrease weight. A solid, controllable shape for all terrains. 52mm x 32.5mm, 101A.