I wore Oura Ring 5 for 24 hours. That solves Ring 4's biggest problem.

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Sometimes the best upgrades are the ones you can't see.

When you wear a chunky smart ring on your finger, size matters. Oura unveiled the ultra-slim Oura Ring 5 in late May, which is noticeably smaller and lighter than the Oura Ring 4 that the smart ring company unveiled two years ago.

Oura Ring 5 is launched with a 40% smaller and thinner design. Oura also adds an extra day of battery to the ring for maximum wear. To achieve this, Oura had to completely redesign the smart ring, replace the battery, improve the algorithm, and insert more powerful LEDs for health tracking.

This is Oura's most substantial update in a generation, as most of the software that arrives in Oura Ring 5 also arrives in Oura Ring 4.

I've been using this ring for a day, and my favorite part about the health tracker is, of course, how small it is.

Ironically, the most noticeable difference between wearing Oura Ring 5 and Oura Ring 4 is that Oura Ring 5 is barely noticeable around your finger. The smaller size of Oura Gen 5 rings makes simple tasks like holding heavy objects or doing the Girl Scout hand sign (pointing your index, middle, and ring fingers together without gaps) much more comfortable.

While wearing the Oura Ring 4, I couldn't fully squeeze my fingers together without leaving a little space between them. This wasn't a big issue with Oura Ring 4. In fact, most people would tell you that the 4th generation Ring's decline in battery life over time is a much bigger problem. But it was annoyingly minor, especially since I wore the ring almost 24/7.

This problem is almost gone in Oura Ring 5. Squeezing your finger creates a bit of space around the ring, which shrinks its size to help it blend in with other real-world analog accessories. This cannot be overemphasized. It looks similar to the jewelry I wear every day.

In fact, when I compared Oura Ring 5 with ZDNET's Kerry Wan wedding band, the thickness and width of the two rings felt almost the same. It may not sound like much, but it's a huge advancement in sensor technology, batteries, and hardware, and the first mainstream example of wearable technology becoming more comfortable and, as the name suggests, wearable.

I’m excited about Oura’s future.

Yes, Oura Ring 5 makes us excited for the future of Oura. But the latest smart ring also gets us excited about all the little bits of technology that could make it do more than just the Oura Ring 5. Because now we know that these devices don't have to be thick and imposing to work.

Since I've only worn the ring for a day, I can't guarantee that the battery will last long. However, we will update this review with that information within a week after we test the claims made about the battery. The same goes for most of the software updates arriving with the Oura Ring 5, including health radar, real-time activity tracking, blood pressure signals, and more.