Built-in mic for acoustics 1/4" input jack for electric instruments Calibration: 430-450Hz, with 1 Hz step | 3 LEDs shows in-tune or mis-tune, LCD meter indicates precision of tuning in cents Pitch Pipe reference tone audible through built-in speaker or earphone jack (earphone not included) Auto shut-off feature saves battery life, tuner powers down if it doesn't sense audio for an extended period of time (non-defeatable) |