The Speedline Alloy Chain Tensioners have a 3/8" Axle hole and will work with most 3/8" or 10mm hub axles. It's single bolt design makes it simple and geeks the pressure and tension uniform. Get your drive-train dialed in with the all-new Speedline CNC'd Alloy Chain Tensioner Kit. Our chain tensioners come in a pack of two, available in a variety of colors, including Black, White, Red, Blue, Polish. Gold, and Green.