Ride Engineering keeps your dirt bike running straight and your chain tight with their trick axle blocks. This unique design utilizes a CRF450 axle (P/N: MX-AXL25-KT - required) allowing the left axle block to float similar to the Japanese design (a concept developed by Ryan Dungey and the KTM factory motocross team) with claimed advantages of better tire traction and more straight line stability in whoops. The Ride Engineering Axle Blocks are constructed out of billet aluminum for lightweight durability. Precision machined for a better swingarm fit and more accurate chain alignment (reduces "rocking"). Unique design allows easy chain alignment with tabs that have markings that can be easily seen and measured off the end of the swingarm. Blocks are 2 mm shorter than stock for more gearing options. Sold as a set.