The Planet Waves Universal II Chromatic Tuner precisely tunes guitars, basses, and other stringed, woodwind, and brass instruments.Built-in microphone for acoustic instruments and 1/4" input for electronic instruments Dual-mode operation for Auto or Manual tuning LCD and LED displays for tuning in both well-lit and dark environments A440 calibrated. May be user-calibrated to any pitch from A435 to A445 Requires one CR2032 battery (included)