Gentex SPH-4B Dual Visor Helicopter Pilot Flight Helmet - Regular For Sale

In 1970 the U.S. Army fielded the Sound Protective Helmet No. 4 (SPH-4) as its new aircrew helmet and, with improvements, it has been used continuously since that time. (at least to 1991) The SPH-4, a single visor, lighter weight version of the Navy SPH-3, replaced the two Army aircrew helmets then in use: The Navy-developed Aircrew Protective Helmet-No. 5 (APH-5) and the Army-developed Antifragmentation Flight Helmet-Nc. 1 (AFH-1). Both helmets were deficient in noise attenuation and retention capability. The SPH-4, which was specifically designed for sound protection, provided (and still provides) superior sound attenuation, but the 1970 version provided no more impact protection than the APH-5. As the sciences of crashworthiness and head injury prevention developed, it became evident that head injuries could be reduced by modifying the SPH-4. Developmental changes improved the impact protection provided by the SPH-4 and led to the development of the Head Gear Unit-56 for Personnel headset, visor, and