You Might Also Like:

Browse Watches By Kind:

For More Information:

Other Places of Interest:

Seiko F231-4009

The world's second thinnest digital watch in 1979


In 1979, thin was in. At 4mm thick, Seiko's F231 was the second thinnest watch of its time and was Seiko's was of demonstrating its mastery of quartz technology.

The 1970s were very hard on traditional watchmakers and that period became known as the "Watch Wars" as new quartz watch technology pitted low cost semiconductor technology against the traditional high quality mechical movements. Many estabilished Swiss companies that were initially relucant to embrace quartz were soon scrambling just to survive. At the end of the 1970s, the Swiss were bent on showing that they not only could compete in the new digital era, but that they had the upper hand in technology. At the end of the 1970s, a war was on to produce the thinnest watch as a means to demonstrate technical dominance.

The Seiko F231 is a very refined watch. It features a 6 digit display, shows the day of the week using alphanumeric characters, and has a fine matching bracelet. The F231 is so comfortable to wear that you hardly even know that it's on. Because of its thinness, neither the F231 or any of the other ultra thin watches featured a backlight.

One of the most unique features of the F231 is the technology used in the reflector behind the LCD display. The F231-4009 features an LCD reflector made up of textured metallic micro reflectors which makes the display easier to see from the side.


Case: Excellent.
The case is in excellent condition, with the original plastic sticker on the back. The polished front bezel is in excellent condition with just a small scratch on the top and a few very tiny places where the plating is wearing thin. The polished surfaces are smooth and the buttons are perfect.

Face / Hands: Very good.
The purple front face is in near perfect condition.

Crystal: Excellent.
Virtually perfect with no visible scratches or scuffs.

Band / Bracelet: Very good.
This Seiko bracelet is original and is just a hair shy of mint condition with no kinks, or dents (and is very comfortable). It fits a full sized 8" wrist.

Function / Accuracy: Excellent.
All functions work perfectly. Digital quartz accuracy.