I have a pro-tec, and its got an ace of spades and a guys signature on it, cant remember what model it is lol. The foam is this "plasticy", compressable foam, and you can bend and twist it and stuff, so I imagine thats why it doesn't crack on inpact, but of course it wasn't designed to, unlike the other helmets, that probabley do offer a better degree of protection to some point, but ah, I like my "turtle shell."
I have the same helmet as someone here on the forums, I think I remember him saying it was CPSC and all that, I'm not sure though... When it gets here (its still on a shipping barge on its way over) I'll be sure to double check it... don't want my mellon to be mush lol