ZDNET's key takeaways The RingConn Gen 2 is a subscription-free smart ring that retails for $300 It monitors your sleep, activity, stress, and vitals, and it's got a marathon battery life The only downside is the user interface feels underdeveloped. View now at Amazon Most smart rings these days claim to offer marathon battery lives, but end up falling short of their promise. Take the Oura Ring 4, for example, which claims to have an eight-day battery life, but often only lasts me around four days tops. I still love and willingly recharge that ring, but part of the appeal of smart rings, compared to smartwatches, is their longer battery life.If you want a smart ring with a truly competitive battery life, I've got one for you. I've been testing the RingConn Gen 2 smart ring that boasts a marathon battery life of 10 to 12 days. The smart ring comes with other perks and a few drawbacks that I'll get to below. details View at Amazon Right off the bat, the RingConn 2 has some green flags. Unlike competing smart ring brands with products that start at $350 and go all the way up to $400 or $450, this smart ring costs $300 and does not require a subscription to gain full access to your health data. Sizing starts at size six and goes through size 14, and you can get the ring in three colors: silver, black, and gold.The build of the ring is more square than circular, but I found myself unbothered by this unique shape. It fits comfortably around my finger with no problems. Despite healthy and frequent wear, the ring doesn't tarnish easily either.The RingConn Gen 2 comes with a case that extends its already impressively long battery life, powering the smart ring's empty battery for over 150+ days. As someone who is constantly charging several wearable devices at a time, this long-lasting charging case that I could use without hooking the smart ring up to an outlet made me partial to RingConn.Most smart rings offer up daily scores for two to three important health metrics: sleep, activity, and readiness. Readiness is calculated based on yesterday's activity, how you slept, and other biometric data, like how late your heart rate dropped as you slept.The RingConn Gen 2 measures your vitals, sleep, activity, and stress, but doesn't measure readiness. Instead of readiness, it provides a Wellness Balance feature. It takes all of the aforementioned data and displays it in a flower-like graph, with longer petals for the biometrics that are meeting or excelling the recommended benchmarks and shorter petals for those that aren't. When all your petals are the same length it indicates that your wellness is at equilibrium. I liked that I could see all the important data displayed in such a digestible and visual manner, right as I opened the app. RingConn's Wellness Balance compiles your activity, sleep, vitals, and stress scores into a holistic illustration of your health. Screenshot by Nina Raemont/ZDNETHardcore trainers use the readiness or energy feature on their smart ring apps to gauge how intense their exercise regimen should be for the day. If that's you, you might be displeased with the Wellness Balance functionality, and I'd recommend the Oura Ring, Ultrahuman Ring, or Galaxy Ring instead.The app delivers your scores alongside context that helps inform the reasoning behind your sleep or vitals score. I was ill one day while testing the ring and spent the entire day sleeping. Because of the large amount of time I spent in bed, it told me that too much sleep can slow down my metabolism or lead to weight gain.Also:Your next Apple Watch or smart ring could have a feature that transforms healthcareRingConn says that the battery on its second-generation ring lasts up to 10 to 12 days, but in my testing, I found that it only lasted seven. Still, that's far longer than the battery lives of other smart rings I've tried, which last four to five days on a single charge. I can say without a doubt that this smart ring has the most impressive battery life out of every brand I've tried.The RingConn Gen 2 also boasts a sleep apnea detection feature with 90.7% accuracy, according to its website. If you're a chronic snorer looking to learn more about how your breathing impacts you throughout the night, the sleep apnea feature could help monitor your conditions and answer some of your questions. It tells you when there are significant or minor outliers in your sleep throughout the night, not only providing a graph that details this but also a timeline that shows when your SpO2 fluctuated during the night.I wore the Oura Ring 4 in tandem with the RingConn Gen 2, and found that the latter seems to underestimate both time spent asleep and the steps I've taken throughout the day.The RingConn and Oura both ranked my sleep efficiency in the 87th and 88th percentile. Oura said I got 11 hours and eight minutes of sleep, while RingConn said I spent 10 hours and 50 minutes asleep. RingConn reported 11,091 steps while Oura reported 15,259 steps. I've seen in various Reddit threads that the Oura Ring tends to overestimate step count, which could account for the great disparity in steps between rings.On a healthy night of sleep, Oura recorded eight hours and two minutes, a sleep efficiency of 94% and a sleep score of 90. RingConn recorded an 84 sleep score, seven hours and 45 minutes asleep, and a 91% sleep efficiency. In both cases, RingConn is subtracting around 15 minutes from my night's sleep.ZDNET's buying adviceI enjoyed most aspects of wearing this subscription-free smart ring, and with a price of $300 ($50 less than competitors), it's a smart ring I'd recommend to those looking for an alternative to Oura's subscription-based services. Especially if you want a smart ring with a battery life that will actually last you a week before recharging.The one area where I noticed RingConn's smart ring lacking was in its user interface. The app feels underdeveloped, and some of the messages lacked personal context that proved they were being generated off of my own data. On one good sleep score day, all that it said when I clicked into the sleep tab was: "Good sleep makes you happy." That's my only true gripe, and I hope the recommendations can become more tailored and informative in future software updates.Otherwise, the RingConn Gen 2 is an impressive smart ring with comprehensive health metric monitoring that's on the cheaper end of the smart ring spectrum. It accurately tracks sleep with features like sleep apnea monitoring that could help you uncover your snoring patterns, it's got a marathon battery life (plus a charging case with 150 days' worth of juice in it), and a build you can wear comfortably.Featured reviews