When you're brewing with an AeroPress you can choose any one of a range of grinds then change the extraction time to suit...a finer grind will allow for a quicker extraction time while a coarser grind needs a longer one.
We don't list a set AeroPress grind on our website as there are so very very very many ways of brewing an AeroPress that we don't want to say that 1 grind will work for them all, only need to look at websites like Brewmethods and World Aeropress Championship to see the kind of things people are doing and imagine the range of grinds you'd need for all those different methods.
We'd say the best way to get your coffee ground just perfectly for our AeroPress recipe here is to order Fine Filter 220g from the drop down box on the product page :)