Acoustic Guitar Two-Way Humidification System. This all new, reformulated, patented two-way humidification system maintains 45-50% relative humidity which eliminates all maintenance and guesswork.
Even optimum humidity for your expensive instrument
Here in Upstate, Western New York winters are desert dry. RH is in the 30 percent range indoors. We have central humidity in our furnace setup and I have another single room humidifier parked next to my three cased Collings acoustics.
I have found that these guitars, with this product, don't stray from tuning, which is a good measure of change in humidity conditions.
IMHO The packs are easy to use and, for the money, if they can keep an optimum RH in my guitar cases, they are well worth it.