Designed specifically for acoustic guitar, ukulele, and other acoustic instruments, the D'Addario 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. It?s so small, convenient, and accurate, you?ll want one for every acoustic instrument you own!