Features: Rhinestones studded couple's Rings, simple stainless steel intelligent Rings, can monitoring heart rate, blood oxygen, and sleep quality, providing health data analysis. Quality stainless steel material, IP68 waterproof, stylish design, suitable for daily wear. High precision intelligent chip, low power consumption, can be used for long time. Magnetic fast charging, build-in 18mAh battery, long standby time. Suitable for daily activity, work, exercise, and night sleep, ensuring that you always aware of your health status. Specifications: Material: Stainless Steel Size: 7, 8, 9(optional) Size 7: approx. inner diameter: 17.3mm/0.68inch, circumference 54.4mm/2.14inch Size 8: approx. inner diameter: 18.1mm/0.71inch, circumference 56.8mm/2.23inch Size 9: approx. inner diameter: 18.9mm/0.74inch, circumference 59.3mm/2.33inch Model name: Intelligent Rings Waterproof rating: IP68 Charging: magnetic charging Battery: 18mAh battery Working hour: 3-7 days Package Includes: 1 Piece Intelligent Rings note: Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.