How to divide the protection grade of body armor?

Body armor is a kind of protective equipment used to wear the human body to avoid shrapnel damage during combat. The difference in material makes the bulletproof level also different. The following is a brief introduction by XINXING police equipment: The most commonly used body armor is the American NIJ standard. There are 6 levels in this standard: level Ⅰ, level ⅡA, level Ⅱ, level ⅢA, level Ⅲ, level Ⅳ. The protection capability ranges from low to high. Among them, Class IIIA requires 9mm pistol bullets that can prevent micro-shooting, and the bullet speed is 420m / s; all levels below Class IIIA are anti-9mm pistols, and the bullet speed is less than 360m / s. Most foreign customers require that the protection level of the body armor is ⅢA. The Ⅲ level protection is to add two 300mm * 250mm ceramic composite plates before and after the body armor, each plate has a thickness of 18mm and a weight of 2.6kg. This level requires It can resist M80 bullets (7.62 * 51 bullets, bullet speed: 800m / s). At this level, there are ordinary bullets fired by AK-47 and 56 rifles. Class Ⅳ also requires the addition of ceramic plates. The thickness of the plate is 21 mm and the weight is 3.3 kg. It requires an armor-piercing projectile that can withstand M1 firing, and the projectile speed is 850 m / s. Body armor ⅢA and below is soft and does not require ceramic plates. The material of the bulletproof layer of soft body armor is divided into domestic and imported materials. The domestic material is white ultra-high-strength polyethylene fiber; the imported material is Kevlar (KEVLAR) yellow; the price of body armor is related to the materials used, and also to the protective area. The larger the area, the higher the price. Common body armor has three types of protection areas: vest type (0.27 square meters), vest type (0.32), and full protection type (with crotch 0.60). XINXING police equipment is equipped with body armor made of various materials. It can be selected according to the actual situation during the combat process. We will definitely be the strongest backing!