Vintage Tavannes Tank Info Sought

Hi all,

I just picked this up at an antique store for very little money, because the owner said it doesn't work. I gave it a bit of a wind and it does in fact seem to run, although it certainly needs a service. I don't know much about the brand, other than some connection to Cyma. Is the DHP on the back with 1938 a personalization, or original to the watch? It is pretty big for a vintage tank. I would love to hear what you all think.

Thanks!

Wow, thanks for the advertising, very cool.

Does yours have similar markings on the back?