Unior derailleur hanger alignment toolthe derailleur hanger and the rear derailleur must be parallel to the rear wheel to enable smooth running of the chain and fast and efficient shifting this tool is easy to use and very precise it is used to check the alignment of the rear derailleur hanger and the wheel and to align the hanger if necessary features material special tool steel the pipe is made of construction steel allows accurate alignment of rear hanger to provide precise shifting ess