Designed to provide a lively and energetic ride, Nipples will revitalize any setup for carving, pumping, dancing, freestyle and freeride. Nipples are poured with the extremely high rebound Randy Urethane formula. Smart People stumbled on this urethane a few years ago while testing ultra high rebound formulas for wheels, but found this urethane to actually be too high rebound for a wheel urethane. Perfect for a bushing. The spec's are: Color/Hardness - Purple 87a, Outer Diameter - 1", Height of Top Bushing -.56", Height of Bottom Bushing -.66". Included is a package to upgrade both of your trucks, 2 upper bushings, 2 lower bushings, and 4 flat washers. Softer washers are recommended for lower speeds while harder bushings will be better when riding fast. Nipple bushings fit Paris, Tracker Fastrack, Gullwing Charger II, and old (pre-2010) Bear trucks. They are not compatible with new Bears, Gullwing Chargers, or Indys. Nipples work with Randal trucks, but they do not sit completely contained in the bushing seat. Since the Randal bushing seat is so low, however, it does not interfere with the performance of the bushings. They fit Caliber trucks, but the lean becomes very restricted past a certain point.