Features: Function: Used to calibrates the tail hook of the Bicycles frame to solve many transmission transmission transmission problems, especially in locating the rear transmission systems. Make of aluminum Alloys materials, anodized, with enhances hardness and reduced weight. Precisions thread, tightly fitting clockwises rotation positioning handle, screw in the bolts and change the lift lugs to lock. Sliding brackets, locking sliding brackets, can adjust the distance between the measuring rod and wheel to measure the deviation between the tail hook and wheel rims. Ergonomic designs allows for easy handling and precise adjustments in bicycles repair. Specifications: Materials: Aluminum Alloys Size: as shown in the picture Package Includes: 1pc Derailleur Hanger Alignment Gauge note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.