Casio crammed a watch into a ring. It measures heart rate, temperature, and oxygen saturation

The smart ring market has settled on an unwritten rule: a ring is a smooth band without a display, which collects data and remains silent until you pull out your phone. Casio decided to break this rule. The new CRW-H001 has a functional dial – and beneath it, sensors you’d expect from Oura.

A watch on your finger, this time with a brain

Casio ventured into miniaturization back in 2024, when it unveiled the CRW-001 ring for the 50th anniversary of its watchmaking division. That one could only do what regular digital watches do – show the time. The new model also received heart rate measurement, blood oxygen saturation, body temperature, and sleep analysis, plus step counting, calorie estimation, and three sports modes for walking, running, and cycling. Menstrual cycle tracking is also included.

Classic watch functions remained: stopwatch, world time, automatic calendar, second time zone, and LED backlight. A vibration motor handles notifications for calls, messages, alarms, and health warnings. Data is collected in the AIZO Ring app, which works on Android 7 and newer, iOS 13 and newer, and HarmonyOS.

The ring lasts approximately four to six days on a single charge, and about 25 days in standby. The display has its own separate battery, which should last about two years – a solution that makes sense because it should show the time even when the sensors run out of power.

Nineteen grams is a lot

Here, honesty is necessary. The ring measures 25.3 × 19.5 × 6 millimeters and weighs 19 grams. Typical smart rings range between two and four grams. Casio is therefore five to almost ten times heavier than the competition, and that’s not just a number from a spec sheet, but something you’ll feel all day.

It hurts the most with sleep. Sleep tracking only works if you leave the ring on your hand at night – and weight is precisely what leads people to take it off before bed. Casio chose a compromise: a display, metal construction, and watchmaking robustness in exchange for comfort. Whether it was a good choice will only be revealed by reviews.

And now for the main point: you can’t buy it

The CRW-H001 is sold exclusively in mainland China for 1,990 yuan, which is approximately 6,200 CZK. Casio explicitly states that after-sales service is also limited to the Chinese market – anyone who imported the ring would have to deal with any potential warranty claims by return mail to China.

There is a precedent for hope. The original CRW-001 ring eventually made its way to American stores, and the company sold the G-SHOCK Nano variant in France, Germany, and the Netherlands. So, expansion is a reasonable expectation, not a promise.

Would you wear a nineteen-gram ring on your finger, or do you prefer the discreet Oura?

Sources: Android Authority, Notebookcheck, The Gadgeteer, Gizmochina