Basis Health Tracker for Fitness, Sleep & Stress - Black (Discontinued By Manufacturer) The most advanced health tracker in the world! Uses 4 sensors, including an Optical Blood Flow Sensor that captures continuous heart rate on your wrist 24/7, Resting Heart Rate during sleep and insights into Stress. Powered by Body IQ technology, Basis automatically analyzes and displays Fitness Activities, like walking, running and biking with the right caloric burn credits. Also goes further than other trackers with Advanced Sleep Analysis of REM and Deep sleep. Data and powerful insights available on your online dashboard. Wireless syncing with select iOS and Android phones, as well as with your PC or Mac. Advanced doesnt mean complex. Our Healthy Habits system helps you set small goals around changes to your daily routine, that add up to a large outcome. Water resistant. Goes everywhere you want to go. Note that Basis is intended as complement and not as a replacement for workout-centric, chest strap-based heart rate monitors.