This article is from the Australia Motorcycles FAQ, by Cameron Simpson cs@zip.com.au with numerous contributions by others.
Snell
This standard was developed mainly for motor-sport helmets, and
helmets which comply with the Snell standard do not necessarily comply
with the necessary Australian Standards. That said, there are several
helmets on the market which comply with both.
The Snell standard tests point impacts at several locations over the
helmet. It's designed to protect against penetration of the helmet
rather than against crushing blows, such as your head hitting the
pavement.
 
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