The Oura Ring 4 launches with improved accuracy, still requires subscription 9to5GoogleThe Oura Ring 4 has slimmer sensors, increased accuracy, and more sizes The VergeThe new Oura Ring 4 is here, and this is what we’re glad they improved CNN UnderscoredOura 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 CNET