dreii/Shutterstock Smartwatches remain popular, but there's a new wearable sheriff in town in the form of a smart ring. These rings are worn around your finger (index, middle, or ring) for accurate measurements and use PPG sensors on the underside to capture vitals, movement, sleep, and more. They can virtually do everything a smartwatch can do passively, with all the data logged in a companion app you can reference for updates. Some people find that a smart ring is sufficient for their needs and have foregone a smartwatch or fitness tracker altogether in favor of this trending technology. Others like wearing both a smart ring and a smartwatch to compare and contrast. Why have an Oura Ring if you buy a smartwatch ? Because you can use the former, from Oura or other alternative brands, as a backup if the latter's battery dies. But there are some things smart rings can do that smartwatches can't, or rather, advantages with them that you don't get with a smartwatch.…