Oura Ring is the revolutionary smart ring that tracks 30+ biometrics including heart rate, heart rate variability (HRV), temperature trends, activity, and sleep – all through a convenient, non-invasive ring. This data is automatically fed to the Oura App on Android or iOS devices to give you actionable insights that can help improve sleep, stress, recovery, movement, and more. The design of Oura Ring 4 is all-titanium, making it sleek, comfortable, and durable. Available in 6 colors and 12 sizes, ranging from size 4-15. The smart ring is ultra-lightweight, weighing 3.3-5.2 grams, and measuring 7.9mm wide and 2.88mm thick. Lithium-ion rechargeable battery that reaches full charge in 20-80 minutes, and battery life lasts up to 8 days. Water resistant up to 100m, Bluetooth Low Energy connectivity, EMF-safe, and non-allergenic.