Any one know what the letter prefix F and A (two different watches) means? Thx.

 

They're the new serialisation (well, nearly new .. Now they're randomised). A is 1999; F was 2003/4.

https://www.bobswatches.com/rolex-serial-numbers

 

Thank you. Very helpful.

 

For future Reference, I have the feeling you might buy another Rolexes
http://www.oysterworld.de/production-dates.html

 

@Canuck
I'm going offer slightly different production years from @jimmyd13
A: 1998
F: 2003