The Fender GreenTuner unit is hand cranked - no battery required! Just crank the knob, and get your instrument perfectly in tune without wasting (or having to pay for) a single battery. The Fender Green Tuner features a built-in microphone and has a 1/4" input. The unit displays the chromatic pitch and indicates if the pitch is sharp or flat. It even has a built-in flashlight!