The Oura Ring Gen 3 Horizon in size 11 is a sleek black activity tracker that includes a charging station and box. With a display resolution of 240 x 240, it provides accurate measurements for heart rate, calories, and distance. The ring is powered by batteries and has a battery life of up to 7 days. It is suitable for indoor and outdoor use and is designed for both iOS and Android operating systems. The ring also features a sleep tracker and includes sensors such as an accelerometer and GPS, making it ideal for running and jogging activities.