3-pack of replacement packets for the D'Addario Two-Way Humidication System (formerly Humidipak), the first maintenance free, two-way humidity control system, made by Boveda, that preserves a constant 45%-50% relative humidity level within your instruments case. This eliminates all maintenance and guesswork. The system is recommended by taylor guitars and others for maintaining the stability and playability of your instrument. 3 replacement packs for the D'Addario Two-Way Humidification System Automatic humidity control protects your instrument against warping, cracks and other damage cause by lack of humidification No more manual adjustments based on seasonal changes, geographic locations, temperature, or other factors Unlike refillable humidifiers Eliminates the guesswork and anxiety of maintaining your instruments proper humidity level No water, no drips, no mess Custom made by Boveda fo D'Addario D'Addario is known for innovative, problem-solving, quality musical accessori