The Smartshock system works in a similar way to an MIPS liner - it has 14 small rubberised \'shock absorbers\' or elastomers that attach to both the EPS foam liner and helmet\'s padding. Because these shock absorbers can flex, the padding is suspended separately to the EPS allowing it to move at just the right distance.Smartshock - 14 Point Smartshock Rotational Protective SystemMulti-Density EPS foam - injection molded with polycarbonateMassive airflow - With an impressive 15 ventilation portsAltec 350g / M-Shell - Expanded coverage while still lightweightSunglass Storage - Integrated sunglass storage systemMulti-point adjustable visor designed - For maximum vision and goggle stowageAnti-Microbial liner - Washable, moisture-wickingAdjustable Ratcheting Fitment SystemNexus Push Release Snap-BuckleColour: Dark GreySize GuideExtra Small - Small 50-55cmSmall - Medium 55-59cmLarge - Extra Large59-63cm