I purchased this in May 2025 and removed it, so I am selling it. Soundhouse sells it for ¥3960. I used it on the 6th string to practice LED ZEPPELIN's MOBY DICK, turning the knob to drop D. Thank you. The Pitch-Key PK-01 is an innovative part that can instantly change the tuning by installing it between the nut and the tuning post (peg) of your favorite string. You can set another preset tuning for a specific string and switch instantly by turning the wheel. It is easy to install and remove, and there is no need to modify the guitar body or remove the strings. For example, you can instantly change from regular tuning to drop D or drop C by simply operating the Pitch-Key. Of course, if you attach a Pitch-Key to each string, you can easily switch between overall tuning down and capo tuning on stage. The Pitch-Key can be attached to almost all electric guitars and acoustic guitars, except for some guitars with special structures, headless guitars, and guitars that use a locking nut. You can instantly switch tunings depending on the part of the song. Instant drop D is of course possible, and you can switch between many tunings. For new tunings, new chord shapes, and a new approach to music. And you can instantly return to your usual tuning. No modification of the instrument is required. You don't need to change guitars during a song to change the tuning.