Both are superb in their own right. This is not meant as a competition but merely a comparison. Both are worthy and should be appreciated on their own and either suffer only by direct comparison. Bottom line: one is not better than the other - both stand on their own merit and on what each represent, respectively. The 3570 is more tool and can be dressed down with is stark white hands while the FOIS can be dressed up better with it's polished chrome dagger hands. The FOIS does wear slightly smaller but the heights are identical. And of course the 3570 has hesalite and the FOIS with sapphire crystal. For me, the crystals fit each watch. I would not want sapphire on my moonwatch and after wearing the FOIS a few days, I would not want hesalite on it - the sapphire works just as well on the FOIS as the hesalite works on the 3570. First - the obvious. Straight lugs on the FOIS and twisted lugs for the 3570 Next is the chrono hand - again, straight on the FOIS while the 3570 features a lured diamond tip Raised logo on the FOIS and the printed logo on the 3570. Also "Professional" on the 3570 dial and less text on the FOIS Casebacks: We all know and love the 3570 while the FOIS proudly displays the Seahorse and the Date of the Wally Schirra space mission Now on to some of the subtle differences: The 3570 is 42 and the FOIS hits at 39.7mm - the bezel overlaps the case of the FOIS while the 3570 case extends beyond the case The 3570 has built in crown guards while the FOIS goes old school with none: From underneath - note the difference in the size of the crowns and pushers, too The 5 minute lume parkers are different: shorter and fatter on the 3570 and longer and thinner on the FOIS. Also note there are fewer minute makers on the FOIS. To me this gives the FOIS a more "refined" look The printed numbers on the FOIS chrono sub-dials are also slightly more refined being the same font but a little thinner. Note how the markers on the 3570 extend into the recessed area but the FOIS markers stop on the "edge" Well, there you have it.