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Ollee Watch One is a replacement circuit board for the Casio F-91W and other watches built around Casio Module 593. It keeps the familiar case, LCD, buttons and minimalist appearance, but adds Bluetooth Low Energy, phone-based time synchronization, activity tracking, extra watch functions, a programmable NFC option and an RGB backlight.
That makes it a connected digital watch—not an Apple Watch in an F-91W case. There is no touchscreen, GPS, cellular connection, conventional optical heart-rate sensor or documented full notification experience. The appeal is simpler: retain the F-91W format and battery-friendly character while adding selected smart features.
What Ollee Watch One actually replaces
Ollee Watch One is not a strap, external accessory or firmware update for the original Casio. The watch must be opened and its original circuit board removed. The Ollee PCB then goes inside the existing movement enclosure, allowing the donor watch’s case, LCD, buttons and general appearance to remain in place.
Ollee says it is an independent company and is not affiliated with or endorsed by Casio. Casio watches are used as compatible donor hardware. The officially tested models are the F-91W, A158W, F-84W, A159W, A171W, W-59, A163W and A164W. The broader compatibility rule is Module 593, but a similar-looking digital watch is not automatically suitable: case geometry, display alignment, battery contacts and retaining hardware can differ. Check the official compatibility and setup information before buying a donor.
#1 Best Overall
- Made of High-quality PU, waterproof and sweat-proof, comfortable to wear, safe and secure, durable
- Compatible with F-91W model watch band
- Use premium Stainless steel Buckle,durable
- Replace your strap with our multi-color resin strap for a new look. It is an excellent original replacement. We have perfect after-sales service, please rest assured to buy
- Please make sure your watch model is listed in the description before purchasing, If not, please contact customer service
For the least risk, use an authentic compatible Casio. A visually identical inexpensive or counterfeit donor may not have the same internal construction.
What features does the board add?
Timekeeping and traditional watch functions
Ollee adds automatic clock and calendar synchronization through its mobile app, along with world time, configurable alarms, chime, hourly beep, snooze and a timer. It also includes event logging, a logging stopwatch and counter functions. Multiple watch-face applications are available, although the display remains the original small segmented LCD.
A six-character programmable name tag gives the watch another small personalization feature. Firmware can be updated wirelessly through Bluetooth, allowing the feature set to evolve without replacing the board.
Activity and health features
An accelerometer enables gesture sensing, step counting and daily activity goals. The app can display history and charts, and Ollee lists integration with Apple Health and Google Health Connect.
The heart-rate feature needs careful explanation. This is not continuous optical heart-rate tracking. Ollee’s pulsometer function uses a manual pulse-counting method to calculate an estimated beats-per-minute result. It should not be treated as medical data or as an equivalent to the sensor system in a fitness tracker.
The board also measures ambient temperature. As with the other activity features, readers should regard the manufacturer’s feature list as a description of what the product supports—not as independent proof of accuracy.
Bluetooth and the phone app
Bluetooth Low Energy is primarily used for synchronization, configuration, data transfer and firmware updates. Most basic watch faces and functions work without a phone connection, but some features depend on the app.
For example, the Sunrise/Sunset face requires phone location data. Activity, health and event history require an account, while basic use does not. Official materials do not establish Ollee as a conventional notification-mirroring smartwatch, so buyers should not assume that phone alerts will appear on the F-91W display.
Bluetooth is not necessarily active continuously. On the Clock face, hold the ALARM button to enable it, or tap the watch until the LAP symbol blinks. Bluetooth turns off automatically after an app session by default. An always-on option is available, but it consumes more battery and may be less responsive than activating it manually. The official FAQ provides the current pairing and troubleshooting steps.
Rank #2
- Original Genuine Casio Replacement Watch Strap/Watch Band
- Fits the following Casio watches only: F-105W-1ASV | F-105W-1ASVY | F-105W-1ASW | F-105W-1ASWY | F-91W-3W | F-91WG-9W | F-94WA-8W | F-94WA-9W | F-91WG-9V | F-105W-9V 05W-1AV | F-106W-1A
- Only watch strap / watch band on offer. Does not come with any other part or accessory.
- For easy reference, the model number can be found at the back of your Casio watch.
- Colour: black
RGB backlight
The original F-91W’s modest illumination is replaced by a configurable RGB LED backlight. This is one of the most immediately noticeable changes because it improves the watch’s nighttime usability while preserving the original display and button-driven interaction.
Optional NFC tag
The kit includes an NTAG213 sticker that can be programmed for an NFC action. It is most suitable for pure-resin models such as the F-91W. Ollee says NFC does not work properly with the A158W because its chrome-plated resin and steel construction attenuate the signal.
NFC performance also depends on the phone and the exact position of the phone over the tag’s antenna. Some phones may require finding a small “sweet spot,” and the feature can be skipped during installation and added later.
Is the modified F-91W really a smartwatch?
“Smartwatch” is reasonable shorthand for a watch with Bluetooth, app synchronization and activity data, and it is how the product is positioned. But Ollee is better understood as a minimalist connected watch or a smart feature board for a classic digital watch.
- Touchscreen interaction
- GPS
- Cellular connectivity
- A conventional smartwatch app store
- A conventional optical heart-rate sensor
- A large notification-focused interface
- The broad third-party app ecosystem of Apple Watch, Garmin or Wear OS
The segmented LCD is both the product’s charm and its limitation. Ollee adds functions within the constraints of the original screen rather than turning the F-91W into a miniature phone.
Battery life: months, not days
Ollee lists up to 10 months of battery life with daily activity tracking and default settings. In power-saver mode, with motion sensing disabled, the company claims more than three years.
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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Clear out junk files and repair common Windows errorsFree Scan →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →These are manufacturer estimates, not independently verified test results. Actual endurance will depend on Bluetooth use, gesture detection, backlight behavior, activity tracking, buzzer use and the installed coin cell. Leaving Bluetooth enabled continuously or using the backlight frequently will reduce runtime.
Even with those qualifications, the battery proposition is central to Ollee’s appeal: it preserves the traditional digital-watch experience of replacing a coin cell occasionally rather than charging a wrist computer every few days.
How the board swap works
The official installation guide estimates approximately 10 minutes and says no soldering is required. That may be realistic for an experienced modder, but first-time installers should allow longer. The work involves tiny screws, a gasket, a metal retaining bracket, a battery contact and a fragile LCD and movement assembly.
Rank #3
- 【Compatible Watches】This nylon watch strap is suitable for watches with a 18mm lug width, such as Casio F-84/F-84W/F-91W/F-94W series, Casio F-105/108/A158/A168 series, Casio W-215/216H/217H/218, Casio SGW-300H/400H/500H, etc. Please check your watch model before purchasing!
- 【Adjustable Size】The long nylon strap is suitable for wrist sizes of 6.2"-8.8" (160mm-225mm). Choose the appropriate size, and it is perfect for wearing to school, sports, or sleeping.
- 【High-Elasticity Nylon Material】This watch strap is made of highly elastic nylon, which is soft, breathable, easy to clean, and quick-drying. The strap won't constrict, rub, or irritate the skin, making it an ideal replacement watch strap.
- 【Easy Installation and Removal】This replacement strap features quick-release pins at both ends, allowing for easy installation and removal without any tools, ensuring a precise and secure lock on your watch.
- 【Multiple Color Straps for Your Style】A168 watch straps offer a variety of stylish color options, allowing you to choose the right color to match your daily outfits, suitable for important occasions such as dates, business, and sports.
The required tools are a #00 Phillips screwdriver, 1.4 mm flat-head screwdriver and tweezers.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstall- Place the watch face down and remove the four case-back screws.
- Remove the case back and gasket, noting the gasket’s orientation.
- Remove the battery.
- Lift out the original movement and unclip the metal retaining bracket.
- Remove the original Casio PCB.
- Install the Ollee PCB in the movement enclosure.
- Transfer and refit the relevant battery contact, battery and retaining bracket.
- Reinstall the movement, gasket and case back.
- Test the display, buttons, sound, Bluetooth and backlight.
Do not lose or deform the gasket, scratch the LCD or force the retaining bracket. Test the display before fully tightening the case back. Because opening the watch can affect its seal, do not assume that the original water resistance remains guaranteed after modification unless the manufacturer specifically confirms resealing or testing.
Keep the original Casio board. Retaining it preserves the possibility of restoring the watch later. For complete professionally assembled watches, Ollee says the original Casio circuit board is returned with the package.
Price and buying options
The prices cited in the supplied product listings were seen on August 18, 2026 and can change. Availability also appears to vary: the DIY page indicates stock unless otherwise noted, while the complete-watch page displays a waitlist prompt.
| Option | Listed price signal | What you get |
|---|---|---|
| DIY Ollee Watch One Kit | $54.99 | Replacement PCB and NTAG213 NFC sticker; compatible donor watch supplied by the buyer |
| Complete pre-installed watch | From $99.99 | Donor Casio watch, Ollee board, professional installation and testing |
Buy the DIY kit if you already have a genuine compatible Casio and are comfortable working with small watch components. The complete option costs more, but removes the installation risk and supplies the donor watch. The listing says complete watches are made, tested and shipped from Canada; it also says U.S. orders ship DDP with duties and taxes included. Check the product page for current stock, delivery terms and price before ordering.
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The F-91W complete build includes the NFC tag. The A158W version is not NFC-compatible, although the listing says its tag is included separately.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Common problems after installation
The display stays blank
Check that the board is seated correctly, the battery contact has not moved, the battery is installed correctly and the retaining bracket is fully clipped down. Also confirm that the donor is compatible and that the LCD connection has not been damaged or misaligned. Remove power before reseating parts, and do not force the bracket or case closed.
Bluetooth will not sync
Bluetooth may simply be disabled. From the Clock face, hold ALARM or tap until LAP flashes, then try the app again. Always-on Bluetooth can be enabled, but it increases battery consumption.
The chime is very quiet
The buzzer depends on correct contact with the watch’s metal back or resonator. Community troubleshooting reports describe weak sound when that contact is obstructed or not making proper contact. This is an anecdotal explanation, not a published performance specification.
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Rank #4
- 【Precision Fit for 18mm Casio Models – Snug & Secure】 Designed specifically for 18mm lug Casio watches, compatible with F-105/F-108/A158/A168 series, AE-1000/1200/1300 series, and more (see full list in product images). Precision-molded with perfectly aligned spring bar holes – no shaking, no noise. Stays rock solid even during intense sports.
- 【All-Day Comfort for Any Scene – Gym / Office / Sleep】 Lightweight, flexible, and multi-hole adjustable. Whether you're working out, typing at a desk, or sleeping overnight, you'll find the perfect fit. Sweatproof and dust-resistant – truly comfortable for all-day wear.
- 【Ultra-Soft Liquid Silicone – Breathable & Gentle on Skin】 Made of skin-friendly liquid silicone with a smooth, non-abrasive feel. The inner side features hidden sweat-guide grooves that quickly release moisture during heavy sweat or hot summer days. No sticky or stuffy feeling – gentle even for easily irritated skin.
- 【2-Pack with Two Colors – 10-Second Quick Swap】 Features quick-release spring bars – no tools needed. Wear black for a professional look at work, then switch to a bold color after hours. Two watch styles in one set, at the price of one band.
- 【Sweat-Resistant & Anti-Aging – Great Value Choice】 Anti-dust and anti-oil coating keeps the band clean with just a wipe. UV-resistant and sweat-proof silicone won't turn yellow, harden, or crack over time. Durability comparable to original accessories at a more affordable price.
NFC does not respond
Confirm that the sticker is installed, the phone supports NFC and the donor is a pure-resin model. Move the phone across the case to locate the tag’s antenna sweet spot, and verify that the NFC action was programmed in a compatible app.
Ollee Watch versus the alternatives
Stock Casio F-91W
The original remains the cheapest and least risky choice. It offers proven simplicity and long battery life, but no Bluetooth, app integration, activity tracking or enhanced RGB backlight. Choose it if the F-91W’s minimalism is the point rather than a starting platform.
Sensor Watch
Sensor Watch is the stronger option for people who want to write and customize firmware. It uses a Microchip SAM L22 microcontroller, supports custom watch applications and can be programmed over USB through a UF2 bootloader. Its design leaves sensor selection and expansion to the builder, whereas Ollee delivers an integrated, app-led feature package.
In practical terms, Ollee is more turnkey; Sensor Watch is more programmable and better suited to developers and electronics hobbyists willing to accept a more technical setup.
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F91 Kepler is a more experimental redesign using a Bluetooth-capable MCU and an OLED display. Its documented project state describes roughly 15 days of battery life. That makes it a better fit for builders prioritizing experimentation, an OLED interface and phone features over the original F-91W-style endurance.
OpenCasio
OpenCasio focuses on an open replacement-board approach with environmental sensing such as temperature, pressure, humidity and magnetic heading, while emphasizing low current consumption. It is a project alternative rather than a straightforward turnkey substitute, so documentation, assembly and support may be less predictable than Ollee’s.
Who should buy Ollee Watch One?
Ollee is a strong fit if you want the F-91W’s appearance and button layout, automatic time synchronization, a more capable backlight, step counting, simple activity goals, extra digital-watch functions and months-long battery life. It is particularly attractive to someone who wants a companion app without wearing a conventional smartwatch.
It is a poor fit if you need GPS, reliable medical-grade heart-rate data, continuous optical heart-rate monitoring, a touchscreen, standard phone notifications, a large app ecosystem, a rechargeable battery or guaranteed water resistance after opening the case.
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Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
