RK-C258 H11 Smart Bluetooth Ring With Sleep Heart Rate Blood Pressure Monitoring 1. High-quality sensor chip, with an accuracy of up to 95% 2. Real-time monitoring, can be viewed in the APP 3. Material: stainless steel 4. Function: heart rateblood oxygenwater surface monitoringstepspressuretemperature 5. Working method: Bluetooth connection APP 6. Battery capacity: ring 18mAh, charging box 180mAh 7. Charging time: 2 hours 8. Working time: 3 days 9. Waterproof: IP68 10. Size: 7, 8, 9, 10, 11, 12 11. Product net weight: about 3g 12. This product is manually measured, and there may be an error of 0.1-0.2 mm and 0.1-0.2 g in length and weight; due to display and light problems, there may be a slight color difference. Please refer to the actual product! 13. Note: The shipment only includes the smart ring + charging box, not other items in the picture!