- Size before purchase: Ring sizes 7–14 (8 sizes). Please measure using the corresponding product size to determine the best fit for your finger. - No app subscription fee: Bluetooth connection to your phone enables tracking anytime, anywhere with a free mobile app. Compatible with Android 5.1+ and iOS 8.0+. The app provides a comprehensive dashboard for health and fitness data, and all features are free. The ring also supports smart photo taking and friend adding. - 24/7 health monitor fitness tracker: Highly accurate monitoring of daily steps, distance, calories, sleep tracking, and social features (friends), plus smart photography. Provides detailed insights to help you make data-driven health decisions. - Sleep health analytics: Tracks daily movement and sleep 24/7, including deep sleep, light sleep, and wakefulness. Delivers insights on sleep quality and personalized advice to help develop better sleep habits. - Charging and waterproof: Battery life 3–7 days; full charge in about 1.5 hours. The ring uses a 300 mAh mini charging case providing 15 charging cycles for long-lasting power. IP68 waterproof rating allows daily wear and diving without removing the ring.