I can't find anything marked H13 and if you do a search, neither has anyone else so far. That is why I though it might be the ETH being read backwards on the opposite side of the pill. However if it is really H13, I have no clue and can't find it listed anywhere.
Maybe someone else will pop in and have a clue?
verwon@gmail.com
My information is not guaranteed correct. I do not get them right all the time, but I do enjoy the hunt~