Intelli Digital Metronome/Dual Tuner. Suitable for all types of instruments and voices. Automatic, calibration, and guitar mode. Built-in microphone for acoustic and Line-in for electric. Eight octave tuning range with easy-to-read wide screen meter indicator. 40 to 216 BPM. Strong beat accent with two color LED display. Five rhythms. Seven beats. Automatic power off after 3 minutes. Uses 2 AAA batteries.