Smart ring with smart features. Used for about 3 days. - Product Name: Smart Ring - Accessories: USB charging cable - Color: Silver - Features: Smart features Equivalent to size 18 (Japan) With instruction manual Thank you for viewing. [Blood Oxygen Monitoring - Early Warning for Low Blood Oxygen Plateau] Equipped with a high-precision optical blood oxygen sensor that emits red and infrared light to monitor blood oxygen levels, enabling all-weather blood oxygen monitoring. You can gain a deeper understanding of your blood oxygen saturation and make timely adjustments to your body. [7*24 Hour Heart Rate Monitoring - All-Weather Tracking Monitoring] [Heart Rate Changes] Adopting the X3605 high-precision heart rate sensor, it tracks your heart rate 24 hours a day, allowing you to understand your physical condition during the day, during exercise, and when relaxed, and self-check for irregularities in your heartbeat. [Stylish Design] A smart ring with a high-design that fits seamlessly into your daily life. [Skin-Friendly and Safe Materials] Thanks to the low thermal conductivity of nanocrystals and tens of thousands of CNC grinding and polishing processes, it is silky, skin-friendly, and has a warm, jade-like feel. Only 2.5g! Waterproof Level: IP68 Operating Time: 5-7 days Charging Time: Approximately 60 minutes