Wow, I was intrigued by this CPSC multi-impact issue and I started looking into it and it's more complicated than I thought...
Apparently, from what I can gather here and there on the net, CPSC helmets are made out of hard foam and they protect well against a single big
impact or multiple low
impacts. It won't protect well after one massive impact simply because the hard foam would have cracked.
Non-CPSC are soft foam, they can take more than one impact (because the soft foam doesn't crack) but all these impacts should be low impacts only
(because soft foam protects less effectively). Basically non-certified helmets are not safe.
Now there are also ASTM certified helmet which are said to be mutli-impact as well, but the differences are really not all that clear between those two certifications: it seems from what I read that these ASTM helmets have a thicker hard outter shell that is another protection against multiple impacts as it can withstand more and it doesn't crack like the thin plastic outter shell you can find on bike helmets.
Some helmets are both ASTM and CPSC. The way I understand it is that the outter shell on a ASTM-CPSC helmet is tougher so it can take multi-impacts, while the inner foam is hard foam, so it can take one big blow or multiple small impacts. So the addition of both seems to make it the safest helmet for skating.
This is only info from the net and people can tell whatever on the net... But it's the way I understand things from a few different websites:http://cruzskateshop.com/FAQRetrieve.aspx?ID=54393http://www.xsportsprotective.com/helmet ... guide.htmlhttp://cruzskateshop.com/FAQRetrieve.aspx?ID=54393http://www.xsportsprotective.com/multip ... lmets.htmlhttp://s-onederby.blogspot.co.uk/2012/0 ... elmet.htmlhttp://www.facebook.com/note.php?note_id=39661577613http://www.helmets.org/skatepam.htm