OYO JMT-9009B Backlit Metro-Tuner for Guitar, Bass, Violin and Ukulele JOYO JMT-9009B JOYO JMT-9009B backlit metro-tuner for guitar, bass, violin and ukulele. Stylish minimalist design, tuner products pick up your instrument's string frequency based on the vibration made when you pluck the string. Our tuners are highly accurate and easy to operate. Beat: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 Semitone flat:b, bb; tuning range: 1eb - 8c Frequency: 410-450 hertz Tempo: 30 - 250 bpm Calibrated tuning for guitar, bass, violin, ukulele and chromatic