Highly recommended! A two-way humidity control system that maintains a constant 45-50% relative humidity level. Eliminates the guesswork of when to refill the humidifier. Stops worries about drips or leakage. Requires no manual adjustments based on seasonal changes, geographic locations, temperature, or other factors. Simply place the Humidipak packets with the included pouches into your instrument case, close the lid, and that's it. Made in the USA for D'addario by Boveda.