STEP & HEART RATE & SPO2 & SLEEP TRACKING: The rings continuously tracks and records your body vital all day. When you sport and gym workouts, records your exercise heart rate, steps & calories burned. During sleep, can also professionally interpret the sleep characteristics at each stage and analyzes sleep quality, to help you adjust your sleep habits. Such as Deep sleep, REM sleep, Light sleep and being Awake, helps you determine if you need more Deep Sleep phases.