The park tool dag 22 derailleur hanger alignment gauge is an indispensable shop tool that can be used to both measure and straighten misaligned derailleur hangers solving a high percentage of shifting problems park tool dag 22 derailleur hanger alignment gauge features gauge bar made of heavy gauge chrome plated steel adjusts to fit 20 to 29 wheels replaceable threaded tip upgraded large inner shaft for added strength tighter tolerances for improved accuracy