This device is very powerful for a novice like moi.La implementation is fast, and the indications are well made (a needle to balance too high or too low, and the color changes to green when the agreement is bon.Le system is based on the vibrations transmitted by the rope accorder.Il Simply pinch the tuner on the keys that are used to tighten the cordes.Ce system has the advantage to tune your guitar in an acoustic environment without this embarrassment . I recommend for beginners who do not want to invest a large sum in this kind of tool.