The most advanced activity tracker known to man, UP3™ is packed with state-of-the-art sensors that give you the full picture of your health. Heart Health Sensor measures resting heart rate - a leading indicator of your overall health and fitness level. Workouts are automatically recognized and logged. You'll gain an in-depth understanding of your sleep. All this, in an impossibly small, water-resistant design with a full week of battery life. So you'll need to recharge before UP3™ ever does.