Posted By The toecap The army hat is made of kevlar. It can with stand rounds (bullets). My helmet has been bashed around abit (steady). And it's still in good condition. I dont know however if there is a shelf life or reccomended change period. One point to note is that the chinstrap on the army helme makes wearing more comfortable but its heavier than the normal hard hat. It depends upon the type of protection that is required. Importantly, always keep your helmet clean. You never know who you'll meet.