Casio has introduced the CASIO RING WATCH CRW-H001 in China, a ring-shaped watch that adds health sensors to its metal body. The 19-gram device packs heart rate, blood oxygen and body temperature sensors plus a vibration motor, and still shows the time on an LCD. It sells for 1,990 yuan (about 47,000 yen) in three sizes: S, M and L. Sales and after-sales support are limited to mainland China.
※1 CNY = 23.7 JPY (as of August 1, 2026)
Health sensors arrive on the ring watch
Casio's ring watch first drew attention with the CRW-001 in 2024, a product that shrank the look of a wristwatch onto a finger. That model stuck to timekeeping. The CRW-H001 is the follow-up that brings smart ring technology into the same housing.
It measures three things: heart rate, blood oxygen saturation (SpO2) and body temperature. On top of that it logs steps and calories, analyzes sleep, records and analyzes training, produces health reports, and tracks menstrual cycles. Walking, running and cycling modes are included as well. Read the feature list alone and it is a smart ring.
Casio states on its official site that the product is not a substitute for a medical device, and that the measurements serve only as an aid to general fitness or health management. The numbers cannot be used as a basis for diagnosis or treatment.
Metalwork squeezed into 25.3 × 19.5 × 6 mm
The case measures 25.3 × 19.5 × 6 mm and weighs 19 grams. Ceramic and stainless steel are used for the case and bezel, with mineral glass over the display. Casio credits metal injection molding (MIM) for making the size possible, a process that shrinks the complex shaping of a wristwatch down to ring proportions. The face is finished with mirror vapor deposition to give the dial a silver shine.
The size lineup is as follows. Casio does not offer resizing, so the size has to be chosen at purchase.
| Model | Size | Inner diameter | Circumference | Front width |
|---|---|---|---|---|
| CRW-H001S-8 | 9 | approx. 19.3 mm | approx. 60.7 mm | approx. 19.5 mm |
| CRW-H001M-8 | 10 | approx. 20.1 mm | approx. 63.1 mm | approx. 19.5 mm |
| CRW-H001L-8 | 11 | approx. 20.9 mm | approx. 65.6 mm | approx. 19.5 mm |
Given that a typical smart ring weighs around 5 grams, 19 grams is clearly on the heavy side. Then again, the CRW-H001 is also a watch with an LCD, which makes a straight comparison difficult.
Two power systems, 4 to 6 days for the smart side
Power is split between the LCD timekeeping section and the smart module. The battery for the display lasts roughly 2 years. The smart module, which handles health measurement and Bluetooth, is rechargeable and runs about 4 to 6 days on a full charge, or roughly 25 days on standby. Charging uses a dedicated cable.
The watch functions are complete enough. There is world time (second time), a 1/100-second stopwatch (up to 59 minutes 59.99 seconds), an auto calendar, 12/24-hour switching and a white LED light, with accuracy of ±30 seconds per month. A Time Flash feature makes the time flash daily and on the hour, though Casio notes it may be invisible in bright surroundings and describes it as an entertainment feature. Water resistance is rated for daily use.
A notification device on your finger
A low-power precision motor delivers vibration alerts for incoming calls, message notifications, silent alarms, health anomaly warnings and custom reminders. These are standard on a smartwatch, but sitting on a finger, they are arguably harder to miss.
The companion app is AIZO RING, supporting iOS 13.0 and later, Android 7.0 and later, and HarmonyOS 2.0 and later. Casio does note that some functions are not fully adapted on HarmonyOS 5.0 and later, and that message notifications do not work on HarmonyOS 5 and above. Anyone considering one should check the pairing with their own phone.
A line that traces back to the 1946 ring pipe
On its product page, Casio points to the Yubiwa Pipe, a ring-shaped cigarette holder invented in 1946 by Kashio Seisakusho, the company's predecessor. Worn on a finger while smoking, it became a hit in the years right after the war and helped fund the development of Casio's calculators. Casio frames the ring watch as a return to that starting point, with current technology layered on top.
Health measurement is what the CRW-H001 adds to that line, but the market is China only. There has been no official announcement about availability in Japan or other regions.
Summary
The CRW-H001 adds heart rate, blood oxygen and body temperature measurement, along with smart ring class health features, to Casio's ring watch. Its 19-gram weight and 4 to 6 days of smart function battery life fall short of dedicated smart rings, but reading the time on an LCD and receiving vibration alerts are things only a ring watch offers. It costs 1,990 yuan (about 47,000 yen) in S, M and L sizes, with sales and after-sales support restricted to mainland China.
