F-91W Silver

F-91W Silver

Group Digital
Watchmaker Casio
Model F-91W
Sub-Model/Designation F-91WM-7A
Operating Mode 12/24 Hour
Mechanism Quartz
Display Type Digital
Complications Stopwatch
Countdown Timer
Dual Hours
Tachymeter
Alarm
Date
Day
Moon Phase
Day/Night / AM/PM
Temperature
Tide
Movement Sensor Watch
Hacking / Stop-Seconds yes
Battery CR2016
In Rotation yes
Comment Custom Sensor Watch replacement, with temperature sensor
Notes Time last set/synced: 24 Sept 2026
FC: 1966

https://www.sensorwatch.net/docs/watchfaces/nanosec/
The F screen tells me that if I apply this adjustment, the static time correction value will increase by 0.4104 ppm. (This will make my watch about 12.9 seconds slower per year.)
A long LIGHT press applies the adjustment to the time and updates the static time correction value. This is what I did above. Sensor Watch will be more accurate going forward!
A long ALARM press applies the adjustment to the time but does not update the static frequency correction. This is what you need to do the very first time you use Finetune, when you initially set the exact time.