What is Aramid?   Aramid is a shortened form of aromatic polyamide. There are 2 types:   Meta-aramids Aromatic polyamides were first introduced DuPont as HT-1 and then under the trade name Nomex. This fiber, which handles similarly to normal textile apparel fibers, is characterized by its excellent resistance to heat, as it neither melts nor ignites in normal levels of oxygen. It is used extensively in the production of protective apparel, air filtration, thermal and electrical insulation, as well as a substitute for asbestos. Meta-aramids are also produced in the Netherlands and Japan by Teijin Aramid under the trade name Teijinconex, in Korea by Toray under the trade name Arawin, in China by Yantai Tayho under the trade name New Star and by SRO Group under the trade name X-Fiper, and a variant of meta-aramid in France by Kermel under the trade name Kermel.   Para-aramids Para-aramid fiber with much higher tenacity and elastic modulus was also developed in the 1960s and 1970s by DuPont and AkzoNobel, both profiting from their knowledge of rayon, polyester and nylon processing. In 1973 DuPont was the first company to introduce a para-aramid fiber, calling it Kevlar, this remains one of the best-known para-aramids and/or aramids. In 1978, Akzo introduced a similar fiber with roughly the same chemical structure calling it Twaron. Due to earlier patents on the production process, Akzo and DuPont engaged in a patent dispute in the 1980s. Twaron subsequently came under the ownership of the Teijin Aramid Company. In 2011, Yantai Tayho introduced similar fiber which is called Taparan in China. Para-aramids are used in many high-tech applications, such as aerospace and military applications, for “bullet-proof” body armor fabric.   What is UHMWPE? Ultra-high-molecular-weight polyethylene UHMWPE is a subset of the thermoplastic polyethylene. It is a very tough material, with the highest impact strength of any thermoplastic presently made. It is highly resistant to abrasion, in some forms being 15 times more resistant to abrasion than carbon steel. UHMWPE fibers branded as Dyneema, commercialized in the late 1970s by the Dutch chemical company DSM, are widely used in ballistic protection, defense applications, and increasingly in medical devices, sailing, hiking equipment, climbing, and many other industries. UHMWPE is used in composite plates in armor, in particular, personal armor and on occasion as vehicle armor. For personal armor, the fibers are, in general, aligned and bonded into sheets, which are then layered at various angles to give the resulting composite material strength in all directions. Recently developed additions to the US Military’s Interceptor body armor, designed to offer arm and leg protection, are said to utilize a form of UHMWPE fabric. Brand/product names include Dyneema, Spectra, Tac-Tex and many others.

The suspension system of a bulletproof helmet refers to the arrangement of straps and padding that hold the helmet in place on the wearer’s head. There are several different types of suspension systems used in bulletproof helmets, and they differ in their design and functionality. Here are some of the most common types:1. Fixed suspension system: This is the simplest type of suspension system, consisting of a fixed set of straps and pads that hold the helmet in place on the wearer’s head. This type of suspension system is commonly used in older or less expensive bulletproof helmets.2. Adjustable suspension system: This type of suspension system allows the wearer to adjust the fit of the helmet to their head size and shape. It typically consists of a set of straps and pads that can be moved and adjusted to create a comfortable and secure fit. 3. Modular suspension system: This type of suspension system allows the wearer to customize the fit of the helmet to their specific needs. It typically consists of a set of removable pads and inserts that can be arranged and adjusted to create a custom fit. 4. Ratchet suspension system: This type of suspension system uses a ratchet mechanism to adjust the fit of the helmet. It typically consists of a set of straps and pads that are connected to a ratchet system that can be tightened or loosened to create a custom fit. 5. Dial suspension system: This type of suspension system uses a dial mechanism to adjust the fit of the helmet. It typically consists of a set of straps and pads that are connected to a dial system that can be turned to tighten or loosen the fit of the helmet. Overall, the main difference between these suspension systems is their adjustability and customizability. While a fixed suspension system may be adequate for some wearers, an adjustable, modular, ratchet, or dial suspension system may be necessary for others to achieve a comfortable and secure fit.

Back-face deformation depth: The depth of the back-face deformation of a bulletproof products after being deformed by a bullet impact. The greater the depth, the more likely the user is to have "broken ribs" or others.   FMJ/FMSJ bullet: an all metal armor shell, a common bullet.   JSP/SJSP Bullet: A semi armor soft tip bullet is an ammunition that sacrifices armor piercing performance in exchange for killing soft targets (humans).   JHP/SJHP missile: a semi armored air tip missile, similar to the JSP/SJSP but with stronger soft target killing ability than the Dame.   FMS bullet: an all metal pointed bullet, a German pistol bullet with a conical head that has stronger armor piercing ability.   United States   1) NIJ 0101.06 standard:   The NIJ 0101.06 standard was developed by the National Institute of Justice in the United States to meet the needs of law enforcement agencies for bulletproof vests. The latest 6-version standard was developed in 2008 and will be replaced by the NIJ 0101.07 standard in 2021.   Due to various reasons, this national standard has become the most well-known standard internationally, truly worthy of the title of "Home of the Brave, Land of the Freedom". Moreover, although it is well-known, this standard is still used by American police officers and may not be sufficient in the military field.   The NIJ standard has the deepest back-face deformation depth among all the different countries’ standards.   The depth of the back-face deformation shall not exceed 1.73 inches/44mm.   2) NIJ 0106.01 (modified) standard:   The NIJ 0106.01 standard is a standard for measuring the bulletproof performance of helmets, established by the National Institute of Justice in 1981. In order to save it from falling behind the old regulations of the times, they made some modifications to it at a certain point in time and added the IIIA level based on NIJ 0108.01.   Chinese GA 141-2010 standard    On October 17, 2010, the Ministry of Public Security of the People's Republic of China issued the GA 141-2010 police bulletproof vest standard, which replaced GA 141-2001. It standardized the types of bullets used during testing and modified the requirements for the protective area of bulletproof vests.   The depth of the back-face deformation shall not exceed 25mm.   Russia GOST R 50744-95 new standard   The new standard implemented in 2017 integrates and removes some overly cumbersome old standards, and adds a new bulletproof level - BR6: capable of blocking 12.7 × 108mm 57-BZ-542 API.   The depth of the concave back shall not exceed 16mm.   British HOSDB Standard (2017 Edition)   Its different levels have different BFD depths.   HO1: Can block 9 * 19mm FMJ bullets and 9 * 19mm JHP bullets. There is no requirement for an average depth of concavity, but the maximum depth of concavity shall not exceed 44mm.   HO2: capable of blocking 9 * 19mm FMJ bullets and 9 * 19mm JHP bullets (requiring higher initial velocity of the projectile, which can be understood as pistol bullets fired from long barreled submachine guns/PCCs). The average depth of the depression should not exceed 25mm, and the maximum depth of the depression should not exceed 44mm.   HO3: Can block 7.26 * 51mm NATO (L44A1 or L2A2) bullets and 7.62 * 39mm bullets. The average depth of the depression should not exceed 25mm, and the maximum depth of the depression should not exceed 30mm.   HO4: Can block the. 308 Win (warhead number 480A) produced by Sacco or the. 308 TSX BT produced by Barnes. The average depth of the depression should not exceed 25mm, and the maximum depth of the depression should not exceed 30mm.   SG1: Can block the 12th shotgun. The average depth of the back indentation should not exceed 25mm, and there are no more than three special levels of optional testing for the maximum depth of the back indentation:   Capable of blocking. 357 Magnum flat headed SP bullets. There is no requirement for an average depth of concavity, but the maximum depth of concavity shall not exceed 44mm.   Can block 5.56 * 45mm SS109 (L17A1h or L15A1) bullets. The average depth of the depression should not exceed 25mm, and the maximum depth of the depression should not exceed 30mm.   Can block 5.56 * 45mm (LE223T3) bullets. The average depth of the depression should not exceed 25mm, and the maximum depth of the depression should not exceed 30mm.   German TR standard   The German TR (Technische Richtlinie) was proposed in 2008 based on the VPAM standard, which may be the most common testing standard in Europe. The biggest difference between it and the NIJ standard is that the TR standard tests handgun armor piercing shells, while NIJ does not.   The depth of the concave back shall not exceed 42mm.   SK L: Can block 9 * 19mm DM 41 round head lead core FMJ bullets. SK 1: Can block 9 * 19mm DM 41 round head lead core FMJ bullets, 9 * 19mm QD-PEP II/S special police bullets, and 9 * 19mm Action 4 special police bullets. SK2: Can block. 357 Magnum FMS rounds. SK3: Can block 5.56 * 45mm SS109 bullets and 7.62 * 51mm DM111 steel core bullets. SK4: Can block 7.62 * 51mm P80 armor piercing bullets.