The suction cup design of this tuner pickup allow it to be used with any instrument that has a flat surface, like a guitar, bass, violin, etc. The suction cup is attached to the instrument and as the instrument is played, sound is then transmitted to thetuner. A pickup is better in transmitting sound into the tuner than the built-in mic that comes with the tuner because a mic is more likely to pick up background noise that causes interference with the sound from the instrument.