I am going to keep this simple. This is a picture with two similar watches. In fact it is the same model, Citizen Chrono Master Chronometer Auto Day Date 33 Jewels. It is a long name, but what a watch! The different aspect about these pieces is that one of them is marked 4-520840-Y and the other one is the ACSS2929-Y. Why? Because one is a few months older and the Citizen used ACSSxxxx and the newer version was renamed 4-xxxxxx. (thanks Stephen for the clarification)
The case is exactly the same, entirely polished stainless steel, screw retained case back with the awesome gold eagle inlay medallion. The mineral crystal is slightly domed with a concave inner surface. The crown is signed “C”. The movement is the Citizen calibre automatic 5240 with 33 jewels, beating at 18,000 bph and can be hand winded too. In this case the watch is Chronometer grade but the case number is correct for day date version, Chronometer or not. The lug distance is 20mm and they came either with a mesh bracelet or with a leather strap.
One more difference on these two watches presented here is the dial code, even though they are exactly the same. The hands are the same and so is everything else.
Read more about the regular Chrono Master Auto Day Date (not Chronometer) HERE.