Watches & Wearables / wristwatch
Casio F-91W
D0 No Radio — No radio at all. It cannot phone home.
The unplug test
It keeps telling you the time. There is no pairing, no account, no app, no charging cable, and no operating system that will one day stop being supported. A single CR2016 cell runs it for a stated seven years, and people routinely get ten. The failure mode is a dead battery, and the fix costs about two dollars.
Why this tier: A quartz digital watch built on Casio's Module 593 with no radio of any kind — not Bluetooth, not radio-controlled timekeeping. Nothing in it can transmit or receive.
Specifications
| Account required | none |
|---|---|
| Works offline | fully |
| Forced firmware updates | no |
| Radios | none |
| FCC ID | not checked |
| Local control | none |
| Phones home | none |
| Parts available | yes |
| Availability | in stock |
| Price band | $15-30 (seen 2026-09-02) |
| Vendor risk | 0 / 3 |
Where to buy
Open questions
- Manufacturer specification page timed out on fetch; swap the primary source to casio.com when it can be retrieved, to upgrade this record's evidence from two Class B sources to Class A.
- Casio sells radio-controlled (Wave Ceptor) and Bluetooth-equipped watches under similar-looking model codes — worth adding a short warning about which prefixes carry radios.
Sources
Class A is primary (manual, FCC filing, teardown). Class B is corroborated community reporting. Class C is never sufficient alone.
- B https://en.wikipedia.org/wiki/Casio_F-91W
Module 593 quartz movement, CR2016 cell with stated 7-year life, ±30 seconds/month accuracy, chronograph, alarm, annual calendar and LED backlight. Explicitly no radio, Bluetooth, or smart capability. In production since 1989 and still made. — accessed 2026-09-02 - B https://blog.creationwatches.com/watches/casio-f-91w-complete-guide.html
Independent corroboration of the specification set and of continued current production, with no connectivity features in the model. — accessed 2026-09-02
History
- 2026-09-02 — First published at D0 on two Class B sources; Class A pending.
Last verified 2026-09-02 — 4 days ago.