Size: 6 Gen3 Charger included I’ve had this Oura ring for 1.5 years, and works the same as the day I bought it. I haven’t been wearing it so decided to sell. When I was interested in purchasing I templated buying used but was concerned with the quality and performance. I wish I would have bought one used because in my opinion it’s not worth the retail cost. To sync, you download the Oura app, create an account and sync the ring. Very easy :)