Originally a civilian design for an enclosed, environmentally-sealed breath mask/hardhat combination, the headgear that became the Recon Grenadier helmet was initially intended for exploration in hazardous environments and underground caverns. With a novel four-filter, "double rebreather" configuration, it was designed to protect the user from poisonous atmospheres, caustic gas deposits, radiation, and pathogen exposure; as well as the more mundane dangers of falls and blunt-force impacts.