Buying a gen Panerai rubber strap is something that requires knowledge and experience with both gen and rep rubber straps.
Both gen and rep rubbers traps have gone thru at least 4-5 iterations, they all may look the same but in fact they aren't. The original 1st gen Panerai genuine rubber straps were of poor quality compared to recent ones, they were sticky and attracted dust easily. They also developed that shiny polished finish prematurely. Quite funny for a $120 rubber strap. Not to mention they came with a black leather floating keeper (not rubber), that most of the people subsribe to replica Pam rubber straps, and think the rep rubber straps are inferior to their genuine counterparts on that account alone.
Second generation genuine rubber straps were more matte in finish, and featured rubber keeper. 3rd gen came with a rubber keeper that was kept losely in place with 4 small "ears". This is the rubbers trap that you'll get on your Panerai genuine watch today. The imprinted Officine Panerai font, style and horizontal groove configuration changed as well, the fact not many people noticed or know about.
Then add to this list a new Seiko/Citizen stylle vented rubber strap used on 243 etc...the head spins...
Panerai replica rubbers straps were and are as good as their genuine counterparts and they're spot on, both in design and rubber quality, it all depends which genuine series rubber strap they replicate. I myseld own 5 different rubber Panerai replica straps (move most of my watches to them during summer, and love them to bits). I also own 3 types of rubber straps for deployants. So you can see how difficult it comes when someone tries to identify a specific Panerai rubber strap, being a gen or a rep.
Hence my comment above - be VERY VERY careful when you buy a so called "genuine" Panerai rubber strap, as you can find yourself in a situation where you just paid 300% on top, for a replica strap.
cheers,
babola