Features: Portable and folding guitar or bass tuner that can attache to your keychain or fits in your pocket. Plug-in design, just insert the 1/4 connector into your guitar/bass output jack, then you can use the tuner. Flat tuning allows to drop-tune your instrument down to 7 semitones below the standard A440 pitch. With LED meter, easy to read the tuning information. With a small LED flashlight for on-stage illumination, very considerate design.