This is a D'Addario instrument humidity control product.
I received it from a musical instrument store when I purchased a guitar in mid-2023.
It originally came in a 3-pack, and there are 2 packs remaining.
Manufacturer's description below:
D'Addario Humidipak is a maintenance-free, two-way humidity control system for guitars. It maintains optimal relative humidity levels of 45-50% inside your guitar/bass case. It provides a comfortable in-case humidity environment without the need for manual adjustments based on seasonal changes, geographical location, temperature, or other factors.
*Humidipak is designed to restore and maintain the humidity of your instrument. This product is not intended for dehumidification in high-humidity environments.
Daily Cleaning: Use a soft brush or damp cloth to gently wipe away dirt. Avoid harsh chemicals. For mesh areas, use diluted mild detergent and a soft brush.
Drying: Air dry in a cool, shaded place after cleaning. Avoid direct sunlight or high heat, which can cause fading and glue deterioration.
Storage: Stuff with paper to maintain shape when not in use. Store in a dry, ventilated area to prevent mold. Rotate between multiple pairs to extend lifespan.
Usage Notes: Designed for basketball. Not recommended for hiking, long-distance running, or other specialized sports where different performance features are required.
Good value for the price. The item works as expected and there have been no issues during use. Everything seems to function properly.