D.I.D. (DKK-003 520VX2 Chain and 15/40T Sprocket Kit Fits: Kawasaki ZX-6R Ninja (ZX636) 03-04 D.I.D chain model: 520VX2; chain color: steel; chain length: 108; gearing (front/rear): 15/40 tooth D.I.D's Patented X-Ring design has the best sealing properties of any O-ring chain, D.I.D X-Rings keep the dirt out and lubrication in for the longest wear life The X-Rings twist between the side plates instead of being squished to reduce friction and minimize power loss High carbon steel rear sprockets are heat treated for maximum durability and long life, countershaft sprockets are made from chrome-moly steel for superior strength and durability