Our Billet Aluminum Chain Adjuster Blocks hold the wheel precisely in place while tightening the chain and stay in position even when the axle is removed! Bolt's unique design means only one 10mm wrench is needed to make chain adjustments. Each anodized 6061 aluminum block has easy-to-read laser etched aligning marks for simple adjustments. One block is threaded to utilize the stock axle. M10 stainless steel fasteners come with thread lubricant.