Meet the O2: a compact but versatile device that lets you track your activity/sleep and monitor your environment. The device lets you see real-time temperature, humidity, and pressure data. It fits on your wrist, in your bag or pocket, or anywhere else and tracks your activity, elevation, and more. You can view your activity on your smartphone.
The O2 runs on a CR2032 battery, which lasts up to 90 days. It is compatible with iOS and Android devices. You can find this project on Indiegogo.