The 1013s are an amazing bargain, even today. $13k on a bracelet, $^k to $7k on a strap with gold rolex buckle. 18k 36mm case with 20mm lugs, same basic size as the 18k DateJust and Day Date, but not quite as tall so it lies flatter on the wrist. Intro'd in Sept. 1960 it had the 1560 movement, Dauphine hands and dagger markers. By the mid to late sixties it had changed to the 1570 movement with baton markers and stick hands. In the early seventies it got the hacking movement. Not sure how long after that production stopped. Some came on Oyster bracelets, others on Jubilees, and many on leather straps. They were for the few who did not want the more complicated DJ and DD, as a result they were probably produced in much fewer numbers or ordered by request. Here are a couple of others that I owned, and then let get away...included a pink gold smooth bevel 1012 version (mabe the rarest).