OURA RING 4 CHARGER - This is the only way to charge your Oura Ring 4. This USB-C cable charger is size specific, so be sure to get the size that fits your Oura Ring 4. You can find your Oura Ring 4 size on the inside of your Oura Ring 4. CHARGERS ARE SIZE-SPECIFIC - Your Oura Ring 4 size can be found on the inside of your smart ring.