Realized I've been a bit quite on the forum lately, and even though these arrived just before Christmas I am only sharing now in 2018 as there have been some interest in this rather unusual Seamaster Chronometers. Unusual in that they house the Chronometer rated Cal. 564 quick set movement and also as far I as know a Japan only market destined model (correct me if you think otherwise). I was lucky to pick both up together, one has a the single caseback reference 166.010, and the other with the dual reference 166.010 and 168.024. Note the contrast in the dial, even though the cases are remarkably similar in condition.