With the Korg Pitchclip 2 you can tune an acoustic or electric guitar in the dark. When the tone is pure, the LED light gives green light. Is the tone too high or too low? Then the LED light turns red As you turn the screen towards your view, you can easily read when a tone is pure or false. Do not you want the tuner to be visible to the public? Then turn the display of the meter through the vertical reversing function behind the neck of your guitar. That way, the device is only visible to you.