Where can i buy a combat helmet?

Hi all
I want to buy a functional helmet such as the air force fighter pilots use, i know that exhist this helmets for civilian use, with the oxigen mask and all.
I know that exhist a store on USA, but i dont remember the webpages :-[
Please if some one know where i can buy this helmet i'll be really gratefully

Best Regards
Berserk
I want to buy a functional helmet such as the air force fighter pilots use, i know that exhist this helmets for civilian use, with the oxigen mask and all.
I know that exhist a store on USA, but i dont remember the webpages :-[
Please if some one know where i can buy this helmet i'll be really gratefully

Best Regards
Berserk