I was wondering if anyone knows the difference between the "pure" F91W and the other product numbers? There are the F91W-1YER (which I have), and the F91W-1XY from the Casio-website. I can also find some with only F91W - from a seller who also has the -1YER. The F91W was marginally cheaper than the -1YER.
I tried asking the seller, but they just said "it was the number given by the manufacturer. About price, we cannot offer any discounts".
If there's a difference I want to collect all types, since I just love the watch due to its simplicity, immortality as an accessory and (late) notoriety.