Brilliantly simple - simply brilliant! The Pitch-Key can be attached to a string between the saddle and the mechanism in seconds, allowing for a lightning-fast switch between two different tuning presets for that string. This is done with a quick turn of the knurled knob. For example, with the E6 string: standard tuning E -> alternative tuning Drop D. A small adjustment screw allows for fine-tuning of the string in both the up and down positions, thus enabling the choice of interval. The Pitch-Key does not affect the sound of the guitar; it can be mounted without modification, even without removing the string in question, and just as easily taken off! The Pitch-Key is suitable for most electric guitars and acoustic guitars. Of course, multiple Pitch-Keys can be used simultaneously, opening up entirely new possibilities for alternative tunings. Even though this can become quite experimental, you can return to standard tuning extremely quickly. No manual tuning, no switching between two guitars. From now on, the Pitch-Key takes care of this job. And it does so quickly enough that you can retune within a song, even within a riff, without major distraction! When used with tremolos, it is important to ensure that they are set up so that they do not move with changing string tension. The Pitch-Key does not work with locking tremolos. String gauges from 009 to 068.