Features:High quality Aluminum alloy, fine workmanship, durable, smooth, burr-free.Bicycle speed to the maximum flywheel, may rub onto the wheel. The derailleur hanger extension is a unique device that offsets.the position of your road derailleur to make it possible to run a wide-range mountain bike style cassette.It is an ideal solution for riders looking to convert their road, gravel, cyclocross, or drivetrain bike.It can attain the simplicity and reduced weight of a single front chainring but without giving up the gear range of a double.It is also great for riders with double chain ring bikes that want lower gearing for those ultra steep climbs.Note:1.Please allow 1-2cm error due to manual measurement. pls make sure you do not mind before you bid.