Strange set symbol

[SoniMail]

This weekend I've bought some used cards, and with that I got a Jolteon with a strange set symbol, that I never saw before and I don't even found that in Bulbapedia.

I don't have the card now, so I cant post any pic, but the set symbol is a little pokeball with the number 3 by it sides.
Which set is that?

Thanks! ^^

 

[SoniMail]

Nevermind, just found out it's Pop Series 3.

^^