Packed full of sensors, the Jawbone Up3 isn't concerned about incoming notifications from your phone. It is concerned with your health and fitness. To keep track of it, it uses a new tri-axis accelerometer, bioimpedance sensors, skin sensors, and ambient temperature sensor to track your resting heart rate, sleep stages, and activities and workouts, with more metrics promised in future updates. To make sense of all this data, it syncs with the Up App and its Smart Coach that keeps track of your progress and delivers personalized guidance. And thanks to a water-resistant body and up to a full week of battery life, there's little reason for you to take it off.