Hi guys, I need to call upon the wisdom of the ancients and knowledge of the all-knowing watch Gods in this forum to help me identify the below Audemars Piguet model:

I am considering a purchase for this model at a price I deem as reasonable but would like to do some personal research regarding it first. However, I can't seem to find where to start.
All I know now is that it is a Classic Ultra Thin model, but have no clue on the year or model code.