The latest invention is the ‘Linientreu’ which is designed to push gear adjustment to the next level. Via allen or torx it is attached to the bolt of the rear derailleur. The high performance line laser then shows exactly if sprocket and jockey wheels are aligned perfectly. This not only makes gear adjustments easier and more precise but also tells you if the hanger is bent. A very clever piece of kit and especially useful for bike shops or mechanics setting up bike after bike all day long.
For more information: tune.com