Adjusting chain tension is quick and easy with the new Box Three(TM) Chain Tensioner. With a single-hole "lollipop" design, these tensioners reduce weight and help keep your rear wheel locked in place. Features: - New and Improved - 20mm of Adjustment - Single Axle Position - Slotted for Dropout - ED Black Hardware - Anodized Finish Specs: - Axle Size 10mm (3/8") only - Material 6061-T6 Aluminum - Hardware - Stainless Steel