The head represents approximately 9% of the body area exposed in combat yet receives approximately 20% of all "hits." The desirability of protecting this vital structure would appear self-evident. Helmet design is a complex issue. Factors that designers of United States Army helmets thoughtfully consider include weight, ballistic qualities of the construction material, balance, helmet-to-person interface (comfort), maintenance of vision and hearing, equipment and weapon compatibility, ease of modification, available materials and manufacturing techniques, durability, ease of decontamination, disposability, and cost. The envisioned future role of the infantryman will make the interplay among these factors even more daunting.