Planet Waves NS Soundhole Tuner CT15 is designed specifically for acoustic guitar, ukulele, and other acoustic instruments. The 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.