SpO2 (blood oxygen) tracking. Irregular heart rhythm notifications. Heart Rate info - resting HR high and low rates etc. Stress notifications - stress events are detected. Stress Management Score. Sleep Score. Log glucose levels. Active Zone Minutes. Built-in GPS. Steps distance and calories tracking. Swimproof up to 50 M. Alexa built-in. Battery life of 6+ days. Small band fits wrists 5.5" to 7.1" in circumference. Large band fits wrists 7.1" to 8.7" in circumference. Includes: Small Classic band. Large Classic band. Charging cable.