MoW vietnam bought on gamestop - SP serial for additional ingame content?

[Von Nancy]

Hi
I recently bought the MoW bundle on Gamestop on a nice offer.
I however concluded that the DLC packs for assault squad wasnt a part of the pack

and that the vietnam version was not the "special version" either

However the product serial screen tells that the product key for Vietnam can unlock additional ingame content? what content would that be and where can I enter that code and get my stuff?

Otherwise thanks for a most awesome game with very little bugs so far