This Hygrometer humidity & temperature monitor is accurate, reliable and easy to use. Perfect for Acoustic Guitars, Electric Guitars, Mandolins, Ukuleles, and Orchestral Strings. Monitoring your instrument’s environment is critical to ensure it stays within the manufacturers warranty and to protect your instrument from drying, warping, shrinking or cracking. The design allows you to measure in the acoustic guitar soundhole or inside the case near the headstock or fretboard/fingerboard. You may also place it any room you want to monitor.