Bulletproof helmets are equipment that absorbs and dissipates the energy of warheads, prevents penetration, reduces blunt injuries, and effectively protects the human head. Bulletproof helmets are mainly used to equip troops and police, mainly in Japanese and German two types of helmets. Bulletproof helmets are classified into metal, non-metallic, metal and non-metallic composites by the material of the helmet shell. In addition to the old-fashioned helmets, the main materials for the current production of bulletproof helmets are ultra-high molecular weight polyethylene fiber and aromatic polyamide two materials, ultra-high molecular weight polyethylene fiber helmet is more lightweight, to meet the Ministry of Public Security GA293-2012 "police bulletproof helmets and masks" standard 2 protection requirements The bullet-proof helmet weighs only 1.2kg. Infantry bullet-proof helmets are anti-shrapnel and direct-fire bullets, and are generally required to withstand the impact of 9mm pistol projectiles and shrapnel outside 5m.