Boss TU-3S Chromatic Tuner Pedal Respected TU-3 tuning performance in a more compact size21-segment LED meter with brightness controlHigh Brightness mode enhances meter visibility outdoorsAccu-Pitch Sign function provides visual verification when tuning is completeChromatic and Guitar/Bass modes, with support for 7-string guitars and 6-string bassesGuitar Flat mode supports drop tunings up to six semitones below standard pitchPowered by optional PSA-series adapter; DC Out jack for powering up to seven BOSS compact effect pedals