I suspect this watch doesn't have a caliber 1530 in it. More likely an earlier caliber 1036. OBSOLETE, Don't buy it unless he guarantees the movement is from the 1500 series. With the introduction of what is known as the Explorer 1, Explorer was a name applied ONLY to the dials on that specific model! This is an earlier version, produced when Rolex stamped the year of production inside the case back! Have him send you pictures of the movement clearly showing the caliber, and inside the case back. And while he's at it, also pictures of the case edge between the lugs on both sides showing the model number and serial number. This watch is aimed at someone who has NO IDEA what he's looking at, in my opinion.