RK Racing Chain 2068-058R Silver Aluminum Rear Sprocket and 520XSO Chain 520 Race Conversion Kit Fits: Kawasaki ZX600N (ZX-6RR)/ZX636C, ZX636D (ZX-6R) 05-06/05-06 520 race conversion kit contains: 14 tooth chromoly front sprocket; 43 tooth silver 7075 T6 aluminum rear sprocket; and RK 520XSO-110 link chain RK's new XSO chains offer quality, performance and unbeatable value, for all but the most demanding high performance application Viewed in cross-section, the RK 'RX-ring' has two lubrication pools and seal points versus the single seal point/pool design of a regular O-ring chain All components of the MXZ4 chain are heat treated using RK's exclusive HIT (Heat Induction Transfer) process and include a clip type master link