A revision of NILECJ-STD-0106.00, the standard redefines the classification system and establishes threat levels and test rounds that are consistent with companion NIJ standards for ballistic protective equipment and materials. Ballistic helmets covered by this standard are classified into three types by level of performance. The ballistic threat posed by a bullet depends, among other factors, on its composition, shape, caliber, mass, and impact velocity. The standard defines such technical terms as the angle of incidence, basic plane, coronal plane, fair hit, penetration, and witness plate and describes different types of bullets (full metal-jacketed bullet, jacketed soft point, and lead bullet). Requirements are delineated for test sampling, test sequence, projections, openings, workmanship, ballistic penetration, and ballistic impact attenuation. In addition, test methods are described, including the test equipment for each type of helmet, the ballistic penetration test, and the ballistic impact attenuation test. Five references, diagrams, and technical data are appended.