Early E855 with 12 instead of a JL logo at 12' are very rare (they were the very first E855 and lasted about one year before JaegerLeCoultre introduced the JL logo). Also, Radium ! (hence, no T SWISS T at the bottom)
If you ever decide to part from that one, pls let me know ! At least, however, bring it with you next time we meet ! To gandle & touch will be a pleasure, I predict.. Cheers & Best, hs