Oasis OH-31 HT Tracker for iPhone
Keep track of the humidity and temperature affecting your instrument without opening the case. The Oasis OH-31 sensor uses bluetooth to connect to an app on your iPhone, up to 125' feet apart. The app is free from the Apple App Store (search for HT Tracker), can read up to 7 sensors and lets you set humidity/temperature limits. You'll get alerts if the readings are too high or low. When sensor and app are out of range, the sensor stores up to 20 days of data. The app also keeps track of your long-term humidity and temperature data by day, week, month and year. Sensor includes a clip so it can be attached inside your case.