RK is the leading manufacturer of motorbike drive chains in Japan. For more than 40 years, RK supplies all well-known Japanese motorcycle manufacturers as original equipment. Also in racing RK is the first choice of many teams in the MotoGP, in motocross or even at the Paris-Dakar Rally.  RK MXU:  A special form of O-ring for MX racing. Due to the flat shape of the ring and the small dimensions, the chain remains very slim and light, yet the lubricant leakage over the race distance is avoided.  - UW ring chain (special shape of the O-ring) - for racing - very easy - Leakage of the lubricant is avoided