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 Celebrity-Loved Oura Ring Is Getting Smarter — Here’s When to Order the Upgraded 4th Gen Wearable Hollywood ReporterOura 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