Float along an axle. Replaces the rear wheel on a bicycle for cleaning, transport and maintenance, fix the chain in a suitable position. This is an important tool for cleaning the chain or diagnosing certain derailleur problems. Compatibility: Works with all derailleur and 1/8in chain. Suitable for quick-release and 12mm thru axle bike frames. Convenient & flexible: Allows the bike to be shifted with the wheel removed, and the derailleur can be moved. Easy to use: Simply remove the rear wheel off the bike, Clamp the chain keeper or dummy hub on the dropout. Avoid scratching the frame: It keeps the chain tensioned and away from the frame and paintwork. Used to stop your chain from getting tangled up during transportation or when cleaning your chain, avoids tangle and keeps the frame from scratching..Items from Sheng Xinshun's shop