<p>Guitar Humidifier System - Humidity Packet Maintain Kit - Automatic Humidity Control System - Maintenance-Free, Two-Way Humidity Control System For Guitars Applicable scope: Acoustic Guitar,Classic Guitar,Electric Guitar,Bass,Violin,Cello,Banjo,Mandolin,Ukulele etc. HUMIDIFICATION SYSTEM: Guitar Humidity Packet is maintenance-free, two-way humidity control system for guitar. PROTECT YOUR GUITAR: Protects your instrument against warping, cracks and other damage cause by lack of humidification. TWO WAY HUMIDITY CONTROL: The first two-way humidity control that maintains a constant 45%-50% relative humidity level within your instruments case. AUTOMATIC HUMIDIFIER: It automatically maintains the optimal 45%-50% relative humidity level within your instrument case, eliminating the guesswork and potential mess related to refilling a humidifier. AUTOMATIC ADJUSTMENTS: No more manual adjustments based on seasonal changes, geographic locations, temperature, or other factors unlike refillable humidifiers. color: Black Material: composite material Package Contents: 2 set guitar automatic humidistat (includes 3 refill bags) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +\/- 1-3cm.</p>