Timing belts best suited for use with HKS Slide Cam-Pulleys. Optimised belt strength for each engine application makes the Fine Tune Timing Belt ideal for use with HKS Slide Cam-Pulleys for high power/high RPM engines. Belt strength has been optimised for each engine application. Designed to allow stable belt tension even when heat expansion occurs in the engine Previous timing belt manufacturing techniques have involved applying pressure from the outside to form the teeth. This applies tension to the teeth making them weaker. By forming a mould with the correct shape teeth to begin with allows the teeth shape to be formed without compromising belt strength and can decrease belt skipping on high torque engines. Teeth rubber is made from H-NBR grade rubber for additional strength.