The first two-way humidity control that maintains a constant 45%-50% relative humidity level within your instruments case. Humiditrak™ works on the following Apple iOS devices with Bluetooth™ 4.0 (iOS 7 or greater required): iPhone 4s and higher, iPad Mini, iPad 3rd and 4th generation, iPad Air and iPod Touch 5th generation. The Humiditrak app is available as a free download. Future iOS devices will be supported as they become available. Humiditrak is also compatible with all Android devices supporting version 5.0 or higher and Bluetooth Low Energy. 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 instrument’s proper humidity level. Protects your instrument against warping, cracks and other damage cause by lack of humidification