... made to snap on over a bomber crew's exisiting helmet and visor this is a system for preventing flash blindness. From the early days of the Strategic Air Command it was anticipated that pilots flying in a nuclear combat arena would be at risk of being temporarily blinded by the intense light of nuclear detonations. Both weapons exploding on targets as well as nuclear tipped SAMs and air-to-air missiles were a hazard. A common early practice was to have the aircrew wear an eye-patch so they had one protected eye in reserve. Pull down shades were a low tech solution which left the crew reliant on instrument flying. The pictured helmet was developed in the 1980's. When sensors detected a sudden rise in ambient light levels the coated lenses would electronically be rendered opaque for several seconds.