except that it isn't less. It is designed more efficiently to allow bigger spaces. Giro's have an internal skeleton to provide the same protection in a lighter more vented system.

my old Bell mtn bike helmet.. crappy retention system, not comfortable, small vents... cheap

current Specialized decibel.. good retention system, comfortable, moderate vents. mid priced. discontinued

soon to be current Ionos.. great retention system, comfortable, great vents. slightly more than Decibel was on sale.