Playercards with no description

Does anyone know how to unlock these Vehicle cards?

Are they supposed to have descriptions that give us a hint as to how to unlock them? 

I cannot find any info about them, I assume Tread Lightly is a tank based one, and Ravenous is a Heli based one but no idea what is the criteria. 

I have thousands on thousands of kills (infantry & vehicles) in the stealth helis and plenty of repairs so no idea what I havent done to get this card at least...