Circular Ring 2 unveiled at CES – and it's the end of plastic sizing kits for smart rings

• Circular's new smart ring, the Ring 2, has an FDA-cleared AFib detection algorithm
• It can be sized using your smartphone, with no need for a plastic sizing kit
• Battery life runs for up to eight days, equalling the Samsung Galaxy Ring

The smart wearables scene at CES 2025 continues to heat up, with the best smart rings taking center stage.

Fresh off of Oura revealing a feature that helps users identify a cold or flu, Circular has announced its Ring 2, a next-gen wearable with an Atrial Fibrilation detection algorithm approved by the US Food & Drug Administration (FDA). In a first for smart rings, it also uses an app to calculate your ring size, rather than a plastic kit.

The new ring, which is available in Gold, Silver, Rose Gold and Black, is crafted from titanium and packs an improved ECG sensor powering the FDA-cleared AFib detection algorithm.

Amaury Kosman, Co-Founder and CEO of Circular said "With the Circular Ring 2, we’ve reimagined what a smart ring can be—combining advanced health technology with timeless design and unmatched durability."

It can track heart health for 24 hours a day like most smart rings, and has an eight-day battery life. However, perhaps one of the most exciting features is the digital sizing, which could streamline the process of buying a smart ring.

Say goodbye to plastic sizing kits

In a press release, Circular says that users will be able to use its Digital Ring Sizing function using a smartphone, but doesn't go into how that's handled—although it's safe to assume it'll use some AR features through camera tech. Smart ring users are often advised to wear the plastic dummy rings for around a day, as our fingers swell up and deflate naturally during the course of the day. It'll be interesting to see if digital ring sizing can compensate, or whether it'll lead to a spate of ill-fitting rings.

Smart rings are in a really exciting place right now, with more brands bringing unique features to the table. With the introduction of smart sizing, it could become much easier to order a device without having to measure or order a sizing kit to begin with, potentially helping make the entire product category feel much closer to a smartwatch.

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