This specification covers the requirements for impact r e s i s t a n t
1.2 Classification . The impact r e s i s t a n t , f l i g h t deck crewman's helmets s h all
1.2.1 Size. The cloth helmet s h all be of the following s i z e s :
f l i g h t deck crewman's helmets and components (see 6.2.b).