This Rocktron X-Tune chromatic tuner stomp box for guitar and bass offers multi-light LEDs and lighted notes that make it easy to tune on dark stages. Built into a strong aluminum chassis, the X-Tune has muting for silent tuning and continuous out for live tuning. Handles 12-note tuning and a 7 octave range. The Calibration function sets the tuner unit to match the pitch of any instrument or audio source (like a piano or tape player). Powered by a 9V battery.