1) how do you measure for a helmet? (sm, med, lrg)

2) i know they require a single layer jacket for 11.499-10.000 but.......
can i skip the jacket if i already own level 3 nomex undergarments? they are better protection than the jacket, on the other hand, its not the jacket.

 

Don't know on the helmet size but the undies won't fly, you'll need a jacket.

 

You need the jacket

Helmet sizing
http://www.danscomp.com/products/charts/helmetchart.htm

 

http://www.helmetcity.com/sizing.php

 

nice page