D'Addario PW-HTK-01 HUMIDITRAK

HUMIDITRAK
Bluetooth Humidity and Temperature Sensor
Musical instruments can be easily damaged by large and rapid changes in humidity and temperature. Now you can protect your investment by simply placing D'Addario's Humiditrak with Blustream™ Technology inside your instrument or case. Humiditrak uses a patent-pending Bluetooth sensor to provide a constant stream of temperature, humidity, and impact data to the free smart phone app to alert you of hazardous conditions that can lead to diminished playability, costly repairs, and lost value to your instrument.