Park Tool DAG-3 Derailleur Hanger Alignment Gauge

An alignment gauge is essential for diagnosing and repairing bent or misaligned derailleur hangers, often the source of shifting problems. The DAG-3 features an all-new design, engineered and built to be light, accurate and versatile. The sliding indicator can measure derailleur hanger alignment against bicycle rims from 16-29", and rotates out of the way to clear seat stays, racks, and other obstacles, allowing 360 degree measurement. The long, precision-extruded aluminum body is built to exacting tolerances and provides ample leverage for making adjustments.