Any info on this WoW subscription card.

[Winstral35]

I just recieved this WoW subscription card does anyone of you have any info on this ? Its a one year subscription to world of warcraft. I have heard it is passed out at some special promotions for Blizzard. But how rare is it ? It is unscratched and in great shape.

I have never seen one before and im highly interested in its lore. I saw some US versions but no EU versions. Anyone of you got some information about it ? Its numbers and that kind of stuff