The 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: ŌURA Suddenly Reveals New Sleek, Powerful Smart Ring ForbesOura Nears $500 Million in Annual Revenue and Readies New Ring BloombergOura Ring 4 debuts slimmer design, additional sizes, and improved sensing starting at $349 TechCrunch