IIRC Finger blood pressure monitoring has never been shown to be accurate ‘enough’. Not under ideal conditions, much less built into a ring. IIRC it’s just biology.

The Circular Ring 2, which recently smashed past its $1 million crowdfunding goal, has landed support for blood pressure sensing. The feature will be enabled via an OTA update later this year.

The US Food and Drug Administration issued a warning Wednesday about the risks of using smartwatches and smart rings that claim to measure blood glucose levels without piercing the skin.