Protection level of bulletproof helmets

GA293-2012 "Police Bulletproof Helmets and Masks" [1] Bulletproof level setting: Level 1: anti-piercing of 1964-style 7.62mm pistol bullets (lead core) fired by domestic 1964-style or 1977-style 7.62mm pistols through. Level 2: Anti-penetration of the 1951-style 7.62mm pistol (lead core) fired by the domestic 1954-style pistol.