The Oura Ring 4 has 4 features I'm especially excited about

Oura just unveiled its Oura Ring 4, an update to the crown jewel of smart rings that's been three years in the making. The fourth generation wearable comes with many substantial upgrades, both on the hardware and software sides, that have already impressed me -- even though I've yet to test these features for myself. 

Also: The Oura Ring 4 rolls out with a thinner design and smaller sensors. Here's how to preorder

A handful of especially exciting features --  from a more comfortable form factor to improved stress-tracking -- convince me that Oura is miles ahead of its competitors in the smart ring race. Here are the four new Oura Ring 4 features most worthy of your attention. 

1. No more uncomfortable sensor domes

I've worn the Oura Ring 3, which uses three sensor domes that dig into your finger and gather data. While it isn't terribly uncomfortable, it's not entirely pleasant either; the area around my finger where the domes protrude becomes dry and irritated after long periods of wear. 

The Oura Ring 4's smart sensing technology has a role in changing this design issue. The smart sensors, which use 18 signal pathways (compared to the Oura Ring 3's eight) and an algorithm that tracks health metrics, make data aggregation reportedly more accurate and optimized, eliminating the need for those raised, uncomfortable domes. 

On the subject of comfort, the Ring 4 is noticeably slimmer around my finger. Compared to the Ring 3, which is rounder and juts out, the Ring 4 is flatter and more comfortable for everyday wear. 

2. Eight days of battery life 

The Oura Ring 3 claims to have a battery life of up to seven days. As an avid wearer of the ring, I don't find this to be true. The Oura Ring 3 lasts four to five days, tops. The Oura Ring 4 reportedly has eight days of battery life, which is longer than any smart ring I've tested so far. This extended battery life is possible thanks to -- you guessed it -- the upgraded smart sensors, which optimize health data collection operations within the smart ring.

Also: The Oura Ring 3 is hands down my favorite health tracker -- and it just went on sale

I'll test the battery life for myself to see how accurate Oura's claims really are, but regardless, this is a major improvement that could encourage other brands to raise the longevity of their smart rings' battery life as well. 

3. Expanded sizing 

Oura Ring sizes for the third generation started at 6 and ended at 13. Now, the sizing runs from 4 to 15. This is the most size-inclusive smart ring on the market, thanks to this expansion. 

4. Daytime Stress gets a useful upgrade

Daytime Stress is a helpful feature on the Oura app that uses wellness data like your heart rate to map out the times of the day when your body is under stress. Because stress can come in different forms, whether your heart rate is raised on an hour-long run (positive stress), or whether you just got into an argument with a loved one (negative stress), it can get confusing to look at the Daytime Stress feature and try to make the distinction. 

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Oura is upgrading this feature by taking the tags people enter throughout the day -- everything from drinking your morning coffee, testing positive for COVID-19, going to a social gathering, exercising, and drinking alcohol or smoking -- and mapping these against the Daytime Stress timeline to get a clearer picture of your stress.