Casio unveiled the CRW-H001M-8, its first ring watch with health sensors inside. Heart rate, blood oxygen, body temperature and sleep all get read from the inner surface of the ring. The original CRW-001 from 2024 tracked nothing at all.
Price: 1,990 yuan (About $294)
Where to Buy: Casio China
Sleep tracking is the feature that changes the math, because it only works if you keep the ring on overnight. The Casio CRW-H001M-8 weighs 19 grams. Most smart rings land between 2 and 4 grams, and our own RingConn Gen 3 review put a size 10 on a kitchen scale at 2.7 grams.
That gap matters more than a spec sheet suggests. A ring seven times heavier has to clear the same bar before any sensor data exists to read.
What the Sensors Actually Cover
Casio lists continuous heart rate, blood oxygen, body temperature, sleep analysis, health reports and menstrual cycle management. On the fitness side there’s step counting, calorie estimates, training logs and dedicated modes for walking, running and cycling.
All of it syncs over Bluetooth to a companion app called AIZO Ring, which runs on Android 7.0 and up, iOS 13 and up, and HarmonyOS. A vibration motor handles calls, messages, silent alarms, calendar reminders and health anomaly alerts, which is the part that pushes this past fitness band territory. Casio is careful to note that the health features are meant for general fitness and wellness rather than medical use.
Three Sizes Instead of One, and No More Spacers
Sizing was the weakest part of the original ring watch. Casio built exactly one size, a size 22 finger, then shipped plastic spacers to shrink the fit for everyone else.
The new one comes in small, medium and large. Small is 19.3 mm inner diameter, medium is 20.1 mm and large is 20.9 mm, which Casio maps to ring sizes 9, 10 and 11. That’s a narrow spread next to a ring like the RingConn Gen 3, which ships sizes 6 through 15, but it’s three real sizes instead of one and a workaround.
The spacers are gone, and the reason is probably physical rather than editorial. Optical sensors need skin contact, and a plastic ring sitting between the sensor and your finger would wreck the reading.
How the Hardware Compares
The outside barely changed, which is surprising given how much went inside. The weight is the one number that moved.
- Dimensions: 25.3 by 19.5 by 6 mm, against 25.2 by 19.5 by 6.2 mm on the CRW-001
- Weight: 19 g, up from 16 g
- Case and bezel: precision steel, with mineral glass over the display
- Battery: 4 to 6 days on the smart module, 25 days on standby, around 2 years on the separate watch battery
- Charging: USB, via a pogo pin magnetic charger
- Watch functions: world time, second time zone, 1/100-second stopwatch, auto calendar, hourly time flash, 12/24-hour formats, accuracy within 30 seconds a month
- Water resistance: rated for everyday use, with no figure in meters published
Price and Where You Can Buy It
Casio is launching the CRW-H001M-8 in mainland China first, at 1,990 yuan, which converts to roughly $294. It comes in silver only and ships in a presentation box.
There’s no confirmed international timeline, and Casio says the watch is sold only in China, with after-sales support limited to that market. That matters if you’re thinking about importing one, since a warranty claim would mean shipping it back. Casio has widened distribution on the earlier models over time, restocking the CRW-001 in the US last July and launching the G-SHOCK Nano in France, Germany and the Netherlands, so a wider rollout is a reasonable expectation rather than a promise.
What to Weigh Before You Buy One
Priced against the field, the Casio undercuts the current Oura Ring 5, which runs $399 to $499 depending on finish. Oura also charges $5.99 a month or $69.99 a year for the membership that unlocks the full app, so a first year with Oura lands near $469 against Casio’s flat $294. Nobody has confirmed whether AIZO Ring carries a fee of its own, and that’s the number that decides this comparison.
The catch is the software. AIZO Ring looks like a third-party platform rather than Casio’s own work, since other ring brands already ship with the same app. A health wearable is only as good as what it does with the numbers, and that’s exactly where Oura earned its reputation. Our smart ring roundup and our RingConn Gen 3 review both landed in the same place, that sensor lists are cheap and interpretation is what you’re actually paying for.
The screen is the part every other outlet led with, and it’s genuinely unusual, since Oura and Samsung both leave it out on purpose. We already asked whether that tradeoff pays off when Rogbid put a 0.49-inch OLED on a $50 ring, and the answer then was that a display turns a ring you forget into a small watch you manage. Casio looks like the first established watchmaker to test that idea, and it’s testing it with the heaviest ring in the category.
Price: 1,990 yuan (About $294)
Where to Buy: Casio China
What isn’t in doubt is that the ring watch stopped being a novelty. Casio spent 19 months turning a 50th anniversary stunt into a platform with a gold edition, a G-SHOCK Nano offshoot, a J Balvin collaboration and now a health tracker. That’s a product line, not a gimmick.
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