Smart ring company Circular reveals its Circular Ring 3 seriesThe series contains the more powerful Circular Ring 3 Pro and the slender Ring 3 SlimBoth rings contain NFC contactless payments in addition to health monitoring tools, with the 3 Pro offering blood pressure and ECG functionalitiesThe best smart rings are usually stuffed with health-monitoring features, such as the Oura Ring 5, while some models are specifically focused on a single dedicated task. These include blood pressure monitoring (like the Vital Signal Ring) or NFC payments, acting as a tiny digital wallet that lets you use your contactless credit cards. The Circular Ring 3 series manages to do it all, cramming blood pressure and NFC payment features into a health-monitoring Oura rival. The Circular Ring 3 Pro is a smart ring that 'bridges health, wellness and everyday convenience' by incorporating an FDA-cleared electrocardiogram (ECG) heart sensor, activity and sleep tracking with lifestyle features. These include haptic feedback vibrations used for health alerts and silent wake-up alarms set up via the app, and NFC contactless payments supporting VISA and Mastercard. Finally, you can Jedi-handwave your way through train stations like you've (well, I've) always wanted. Comprised of plated titanium, the Ring 3 Pro packs up to 12 days of battery life and 5-6 additional charge cycles when used with the case. It weighs just 3-4g, depending on size. There's also a Circular Ring 3 Slim, which is (as the name suggests) slimmer by around 0.5mm, which may not sound like much, but is a big deal in terms of ring thickness. You still get health monitoring features, haptic feedback, and NFC support, but ECG and blood pressure features are unavailable. Too good to be true?On the surface, the Circular Ring 3 Pro sounds incredible. However, with pricing yet to be announced and pre-orders yet to go live, I'd need to know more before adding it to our best smart rings list. For one thing, we reviewed the Circular Ring 2 earlier this year and found the software somewhat lacking. Our reviewer Becca Caddy wrote, "Unfortunately, the experience is undermined by unreliable syncing, unfinished features and an app that’s confusing to navigate." Circular needs to overhaul its app if it's going to take on Oura.Second, although its ECG is FDA-cleared, blood pressure calculated through LED technology has only recently been cracked by Apple with its Hypertension feature, Huawei with its Watch D series, and the Signal ring. Otherwise, devices that claim to monitor blood pressure rely on extrapolation from other metrics to varying degrees of success. Can the Circular Ring 3's advertised feature succeed against strong, new competition from Apple and others? I'm not sure, but the only way to know is to test it out when it finally drops.