The D'Addario NS Micro Soundhole Tuner is a chromatic clip-in tuner that mounts inside an acoustic guitar's soundhole via a non-marring clip, staying hidden during performance. A piezo transducer reads string vibration through the soundboard for fast, accurate tuning, and a multi-color display aids visibility in different lighting. It offers an adjustable calibration range and is intended for acoustic guitar and other soundhole instruments.