Formula Four - 93 Duro - Soft Sliders.  The most controllable and consistent sliding soft wheel out. Soft Duro combined w/ High Rebound compound absorbs more impact & vibrations - easier on your body for longer sessions. Holds speed through even the roughest terrain. Reliable grip when you need it. Unmatched Formula Four flatspot resistance. Basically a softer roll with ability to slide. 93A. 58mm. Radials Shape.