Cairns helmet size adjustment

[SHU93]

I was just issued a new helmet which looks the same as my old one but the sizing inside is much smaller. I adjusted the nob in the back to fully open but still tight without my hood or mask. Looking all over the Internet can't find anything on how I can adjust the sizing inside it...it says on Internet it can adjust but doesn't show pictures how? Don't want to mess around with it without knowing what to change. Any help with pictures would be appreciated!

[DeputyMarshal]

I was just issued a new helmet which looks the same as my old one but the sizing inside is much smaller. I adjusted the nob in the back to fully open but still tight without my hood or mask. Looking all over the Internet can't find anything on how I can adjust the sizing inside it...it says on Internet it can adjust but doesn't show pictures how? Don't want to mess around with it without knowing what to change. Any help with pictures would be appreciated!

What does it say in the user manual that's supposed to accompany every new helmet?

[SHU93]

It shows a picture of the interior straps and says it can be adjusted but doesn't really explain how?

[WD6956]

What model of helmet is it?

[MemphisE34a]

Traveling this year? I think they can shrink your head in South America.

[jbrescue]

If it has the defender shield, the interior is actually smaller than what you have had in the past. Also, the 880 is smaller. If this is not the case, use a vise and shrink your melon.