Bike Spoke Ruler Spokes Length Gauge Ball Bearings Measuring Tool Steel Body

The reviewer discusses the AliExpress derailleur hanger alignment gauge at multiple points in the video. They state they have used it for nearly four years and find it fantastic. They demonstrate its use by checking the alignment on the Cannondale frame, explaining the process of comparing the top and bottom of the wheel to see if the hanger is bent. They note it is exactly the same as any other alignment gauge and is used for straightening minor bends or determining if a hanger needs replacement.