Give your classic Casio F‑91W or A158W a secret life as a smart companion without sacrificing its retro charm. The Ollee Watch module is a drop-in replacement that keeps the iconic look and lightweight feel, while quietly packing in Bluetooth, sensors, RGB backlighting, and app-powered features you’d normally expect from a smartwatch.
Why this mod is catching on
The F‑91W and A158W are beloved for their simplicity, ruggedness, and long battery life. Ollee Watch was built by a wearable engineer who wanted modern convenience without a big touchscreen or daily charging. The result is a tiny circuit board that slips into the original case in minutes and brings the watch up to date, all while preserving the original three-button interface.
Smart features without the bulk
– Automatic time sync via Bluetooth, plus world time
– Five programmable countdown timers and a 1/100-second stopwatch
– Sunrise and sunset times using your phone’s GPS through the companion app
– Alarms with snooze and hourly chime, including support for custom melodies
– Fitness extras: step counter, basic heart-rate pulsometer, and ambient temperature logging
– Digital compass heading
– Full-color RGB backlight you can tint to your liking
– NFC contact tag on compatible resin-cased models for quick info sharing
– Handy add-ons like flashlight mode, a tally counter, and simple mini-games such as Pong or Blackjack
Under the hood
Ollee’s custom PCB uses a modern ARM Cortex microcontroller with Bluetooth Low Energy. Power comes from a standard CR2016 coin cell. Depending on settings, you can expect around 10 months with heavy use, or up to about 3 years in ultra power-save mode. That’s not the multi‑year stamina of a stock F‑91W, but it’s impressive given the added capabilities. The companion app on iOS and Android lets you set alarms, choose time zones, tweak LED colors, view logs, and keep everything in sync.
DIY-friendly installation
No soldering is needed. Pop off the snap-on caseback, lift out the original module and battery, and drop in the Ollee board with a fresh CR2016. Carefully reseat the rubber gasket to maintain splash resistance, close the case, and pair with the app. Most users report the swap takes about 5–10 minutes with basic tools like a case opener or small screwdriver and non-magnetic tweezers. The kit includes the PCB and an optional NFC tag.
What enthusiasts are saying
Purists argue that adding features to a minimalist classic defeats the purpose. Tinkerers, on the other hand, say Ollee turns a beloved budget watch into a discreet, connected tool—keeping the vintage face while adding Bluetooth sync, fitness tracking, custom alarms, and a colorful backlight. If you’ve ever wished your F‑91W could do just a little more, this strikes a sweet balance.
Pricing and options
– DIY Ollee Watch module: $54.99
– Pre‑modded F‑91W or A158W with Ollee installed: about $99.99
– Companion app: free on iOS and Android
Bottom line
Ollee Watch is a cleverly engineered upgrade for fans of the F‑91W and A158W who want modern functionality without abandoning the timeless, ultra-wearable design. It keeps the spirit of the original intact while adding just enough smarts to make your dependable daily beater feel brand new.
