Ultrahuman, Ring AIR-Smart Ring Health Tracker Space Silver, size 8 (Sells new on Amazon for $332) This is a used, ;like new Ultrahuman Ring AIR Works great, I cannot wear it at work. It does have a few tiny marks from wear, but they are barely visible. See pictures. 6 days Battery Life Water resistant up to 100m Memory Storage Capacity 0.5 MB Special Feature Sleep Monitor, Multisport Tracker, Activity Tracker, Custom Activity Tracker, Heart Rate Monitor Connectivity Technology Bluetooth DESIGNED TO KEEP YOU MOVING - The 'Movement Index' is designed to increase your non-exercise energy usage through the day. With this all-in-one activity and fitness tracker, you can track steps, workouts and calories for insights into your all-day activity. All features work together seamlessly, to make sure you get the most out of the smart ring. Workout Tracking is now easy, with a dedicated Workout Mode that tracks Heart Rate during workouts — you can get insights into your cardiovascular response, track intensity levels, and make informed decisions to improve your fitness outcomes. ENHANCED RECOVERY - Ring AIR is geared to help you recover better, with focused recovery tracking. The 'Dynamic Recovery Score' is derived from a blend of key metrics including heart rate monitoring, Heart Rate Variability (HRV) and skin temperature that track not only sleep but also every aspect of your lifestyle, giving you actionable insights.