The OURA Ring 4 Smart Ring in Brushed Silver, Size 13 is a versatile and advanced activity tracker suitable for both indoor and outdoor activities. With a high-resolution display and a battery life of up to 7 days, this ring provides accurate measurements for heart rate, temperature, and more. The ring is compatible with both iOS and Android devices and offers features such as goal-setting, exercise logging, and smartphone compatibility. Made from titanium and metal, this durable ring is water-resistant and perfect for gym training, weight lifting, yoga, and running.