Estone Universal General Profession Guitar Cello Clip Line On Piezo Pickup Transducer It is especially designed for guitar tuning.Using it is easy,just clip it to the position where vibration is more obvious on the instruments Built-in vibration sensor The clip is built-in vibration sensor which could make a response to vibrations,then transform them to electric signals and deliver them through cable to the tuner Standard jack dimension Cable length: 92cm approx.