Oura Ring 4 debuts slimmer design, additional sizes, and improved sensing starting at $349 TechCrunchThe Oura Ring 4 has slimmer sensors, increased accuracy, and more sizes The VergeOura announces new smart ring with updated design and new sensors for $349 CNBCOura Ring 4 First Take: More Titanium, Better Accuracy and Longer Battery Life CNETOura Nears $500 Million in Annual Revenue and Readies New Ring Bloomberg