The RingConn 2 monitors your SpO2 levels while sleeping and promises 90 percent accuracy after just three hours of wear. The company is in the process of gaining FDA approval for the feature.
In the meantime, the surprisingly lightweight smart ring has the standard health-tracking features — including sleep, activity, stress, and heart-rate monitoring. It costs $299, claims up to 12 days of battery life, and doesn’t require a subscription.





