SIZE BEFORE YOU BUY - Oura Ring 4 sizes are different from standard ring sizes. Size yourself with the Oura Ring 4 Sizing Kit. OURA MEMBERSHIP - First month of membership is free with your purchase, GBP 5.99/mo afterwards. Membership is tied to your account via the Oura App, not your physical ring. ACCURACY - SMART SENSING - Oura tracks over 30 biometrics, including sleep, activity, stress, heart health, and women’s health metrics. Oura Ring 4 is powered by Smart Sensing, which adapts to you — delivering accurate, continuous data, day and night. LONG LASTING BATTERY - With up to 8 days of battery life, no screens and no vibrations, Oura Ring 4 allows you to focus on the present. From a workout to a night out — you’re free to forget it’s on. Until you start getting compliments. DESIGNED FOR 24/7 WEAR - The updated design of the Oura Ring 4 is more comfortable, fits better than ever, and is water resistant. The first all-titanium smart ring combines exceptional durability with a gentle touch, even for sensitive skin.