Smart ring or fitness watch: Finding the right fit

livemint.com:

₹28,499), a health tracker with a bunch of sensors, including a heart rate monitor, a six-axis motion sensing unit and a skin temperature sensor, all packed into an 8mm wide, 2.4mm thick titanium ring. As with the Luna Ring ( ₹19,999), it’s light and unobtrusive, so much so that one didn’t notice its existence on the finger beyond the first week. It comes in 10 sizes and five finishes; a sizing kit is sent as soon as you place your order to ensure a correct fit.

Build quality is good; I haven’t scuffed my ring in all these months, but I suspect it may not fare as well if you are into lifting weights or working with outdoor tools. These sensors log data on heart rate, movement, body temperature to give you a report card on three scores: Movement Index, Sleep Index and Recovery Score—how regularly you’ve been moving, how well rested you are and your overall state of well-being. While the Luna Ring follows a similar approach (sleep, activity and readiness), the Ring Air’s secret weapon is the companion app, which surfaces your key scores and lets you dig deeper into individual markers.

At any point, you can see your heart rate, VO2 Max (maximal oxygen consumption) and skin temperature, along with little lifestyle nudges. I’ve learnt about my adenosine clearance window, which tells me whether or not I should consume caffeine at a certain time, or how to stay on top of my body clock by knowing the best time get sun exposure or exercise, or my ideal bedtime. Submit to it, and it feels somewhere in between “hacking your health" and “letting an algorithm decide your day for you".