USB-C cable charger is size-specific and can only be used with the matching Oura ring size (ring sold separately) You can find your Oura Ring 5 size on the inside of your smart ring or in your Oura app Charges fully in 20-80 minutes, depending on the current battery level An additional charger is the perfect accessory for vacation, trips, the office, or anytime your battery is running low This charging dock is made by Oura; unauthorized chargers may permanently damage the ring battery