Oura's third-generation Ring is more powerful, but not for everybody

The wearables business is hard, especially if you're a small startup with a device you could, perhaps uncharitably, call "niche." Oura, which makes activity-tracking rings worn endorsed by a numberof celebrities, recently released its third-generation model. This new hardware is a technical marvel, packing many of the features that most wrist-worn devices take for granted. But the need to keep the cash rolling in has seen Oura, like Fitbit, Apple, Wahoo and others, pivot to a recurring-revenue m...