Designed specifically for acoustic guitar, ukulele, and other acoustic instruments, the chromatic Micro Soundhole Tuner remains perfectly concealed within the instrument's soundhole for discreet tuning. The non-marring universal mounting clip allows stress-free installation, while the highly sensitive piezo transducer senses vibrations directly from the soundboard for fast and accurate tuning response. The bright, multi-color display allows easy viewing in any environment. A435-455 calibration range, uses one 3V 2032 battery (note: this tuner does not utilize a battery cover).