The most advanced Jawbone activity tracker known to man, 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. The features of Jawbone tracker band is water-resistant design with a full week of battery life. So you'll need to recharge anywhere anytime. Free Delivery & easy return in the UK .