RK is the leading manufacturer of drive chains for motorcycles in Japan. For more than 40 years, RK has been supplying all major Japanese motorcycle manufacturers with original equipment. Even in racing, RK is the first choice of many teams in the MotoGP, the motocross or the Paris-Dakar Rally. RK KZU: A special form of the O-ring for MX racing. Due to the flat shape of the ring and the small dimensions, the chain remains very slim and light, but the leakage of the lubricant over the race distance is avoided. - U-ring chain (special shape of O-ring) - for racing - very easy - Leakage of the lubricant is avoided