Garmin vivosmart 4, Activity and Fitness Tracker w/ Pulse Ox and Heart Rate Monitor. Size: Large About this item Slim, smart activity tracker blends fashionable design with stylish metal accents and a bright, easy-to-read display.Supported Application:Sleep Monitor,Heart Rate Monitor,Messages,Fitness Tracker. . Wireless comm standard:2.4_ghz_radio_frequency Includes advanced sleep monitoring with REM sleep and can gauge blood oxygen saturation levels during the night with the wrist-based Pulse Ox sensor. (Not a medical device and not intended for use in the diagnosis or monitoring of any medical condition) Fitness and health monitoring tools include estimated wrist-based heart rate, all-day stress tracking, Relaxation breathing timer, Vo2 Max, body battery energy monitor and more Features dedicated activity timers for walks, runs, strength training, yoga, pool swims and others Get vibration alerts for All notifications, including calls, text messages and more (text replies available for Android Device users) Battery life keeps up with you; lasts up to 7 days (excluding Pulse Ox sleep tracking) and is safe for swimming and showering, too Also includes a 3-pack of large replacement watch bands.