All white card

I have a few white cards (all white, no writing on the card) I am wondering if i can use them for something. I don t know much about these programmes but if anyone has any help for me would be great.

I have a mikobu dual cristal 3.68 mhz and a detonator II with a atmel flash.
I think maybe these cards could be old gardien II cards. the cards says when i get info from card that it s a ROM3 Rev 380 but looks to be looked somehow.
anyhelp would be appriciated. thanks all.