Personal armor Personal armour ( also known as personal armor or body armour ) is the whole of protecting clothing , designed to absorb and / or deflect slashing , bludgeoning , and penetrating attacks . They were historically used to protect soldier s , whereas today , they are also used to protect various types of police ( especially riot police in particular ) , private citizens , private security guard s or bodyguards . Two types exist : regular non - plated personal armor ( used by the people mentioned above , except combat soldiers ) and hard - plate reinforced personal armor , which is used by combat soldiers , police tactical units and hostage rescue teams . History . Many factors have affected the development of personal armor throughout human history . Significant factors in the development of armor include the economic and technological necessities of armor production . For instance plate armor first appeared in Medieval Europe when water - powered trip hammer s made the formation of plates faster and cheaper . Also modern militaries usually do not provide the best armor to their forces since doing so would be prohibitively costly . At times the development of armor has run parallel to the development of increasingly effective weaponry on the battlefield , with armorers seeking to create better protection without sacrificing mobility . Ancient . The oldest known western armor is the Dendra panoply , dating from the Mycenaean Era around 1400 B . C . Mail , also referred to as chainmail , is made of interlocking iron rings , which may be riveted or welded shut . It is believed to have been invented by the Celtic people in Eastern Europe about 500 B . C . When these Celts moved West they took mail with them . Most cultures who used mail used the Celtic word " Byrnne " or a variant , suggesting the Celts as the originators . The Romans adopted mail as the lorica hamata , although they also made use of lorica segmentata . While no non - metallic armor survives , a linen laminate known as linothorax is repeatedly mentioned in ancient Greek sources . In East Asian history laminated armor such as lamellar , and styles similar to the coat of plates , and brigandine were commonly used . Later cuirasses and plates were also used . In pre - Qin dynasty times , leather armor was made out of rhinoceros . Chinese influence in Japan would result in the Japanese adopting Chinese styles , their samurai armor being a result of this influence . Middle Ages . In European history , well - known armor types include the mail hauberk of the early medieval age , and the full steel plate harness worn by later Medieval and Renaissance knight s , and a few key components ( breast and back plates ) by heavy cavalry in several European countries until the first year of World War I ( 1914 – 15 ) . Plate . Gradually , small additional plates or discs of iron were added to the mail to protect vulnerable areas . By the late 13th century , the knees were capped , and two circular discs , called besagew s were fitted to protect the underarms . A variety of methods for improving the protection provided by mail were used as armorers seemingly experimented . Hardened leather and splinted construction were used for arm and leg pieces . The coat of plates was developed , an armor made of large plates sewn inside a textile or leather coat . Early plate in Italy , and elsewhere in the 13th – 15th century were made of iron . Iron armor could be carburized or case hardened to give a surface of harder steel . Plate armor became cheaper than mail by the 15th century as it required much less labor and labor had become much more expensive after the Black Death , though it did require larger furnaces to produce larger blooms . Mail continued to be used to protect those joints which could not be adequately protected by plate , such as the armpit , crook of the elbow and groin . Another advantage of plate was that a lance rest could be fitted to the breast plate . The small skull cap evolved into a bigger true helmet , the bascinet , as it was lengthened downward to protect the back of the neck and the sides of the head . Additionally , several new forms of fully enclosed helmets were introduced in the late 14th century to replace the great helm , such as the sallet and barbute and later the armet and close helm . Probably the most recognized style of armor in the world became the plate armor associated with the knight s of the European Late Middle Ages , but continuing to the early 17th century Age of Enlightenment in all European countries . By about 1400 the full harness of plate armor had been developed in armories of Lombardy Heavy cavalry dominated the battlefield for centuries in part because of their armor . In the early 15th century , small " hand cannon " first began to be used , in the Hussite Wars , in combination with Wagenburg tactics , allowing infantry to defeat armored knights on the battlefield . At the same time crossbow s were made more powerful to pierce armor , and the development of the Swiss Pike square formation also created substantial problems for heavy cavalry . Rather than dooming the use of body armor , the threat of small firearms intensified the use and further refinement of plate armor . There was a 150 year period in which better and more metallurgically advanced steel armor was being used , precisely because of the danger posed by the gun . Hence , guns and cavalry in plate armor were " threat and remedy " together on the battlefield for almost 400 years . By the 15th century Italian armor plates were almost always made of steel . In Southern Germany armorers began to harden their steel armor only in the late 15th century . They would continue to harden their steel for the next century because they quenched and tempered their product which allowed for the fire - gilding to be combined with tempering . The quality of the metal used in armor deteriorated as armies became bigger and armor was made thicker , necessitating breeding of larger cavalry horses . If during the 14 – 15th centuries armor seldom weighed more than 15 kg , then by the late 16th century it weighed 25 kg . The increasing weight and thickness of late - 16th - century armor therefore gave substantial resistance . In the early years of pistol and arquebuses , firearms were relatively low in velocity . The full suits of armor , or breast plates actually stopped bullets fired from a modest distance . The front breast plates were , in fact , commonly shot as a test . The impact point would often be encircled with engraving to point it out . This was called the " proof " . Armor often also bore an insignia of the maker , especially if it was of good quality . Crossbow bolts , if still used , would seldom penetrate good plate , nor would any bullet unless fired from close range . In effect , rather than making plate armor obsolete , the use of firearms stimulated the development of plate armor into its later stages . For most of that period , it allowed horsemen to fight while being the targets of defending arquebuseers without being easily killed . Full suits of armor were actually worn by generals and princely commanders right up to the second decade of the 18th century . While heavy , it permitted mounted commanders to survey a battlefield while providing safety from musket fire . Horse armor . The horse was afforded protection from lances and infantry weapons by steel plate barding . This gave the horse protection and enhanced the visual impression of a mounted knight . Late in the era , elaborate barding was used in parade armor . Gunpowder era . As gunpowder weapons improved , it became cheaper and more effective to have groups of unarmored men with early guns than to have expensive knights , which caused armor to be largely discarded . Cavalry units continued to use armor for longer . Example include the German Reiter , Polish heavy hussars and the back and breast worn by heavy cavalry units during the Napoleonic wars . Anachronistic use . Metal armor remained in limited use long after its general obsolescence . Soldiers in the American Civil War ( 1861 - 1865 ) bought iron and steel vests from peddlers ( both sides had considered but rejected it for standard issue ) . The effectiveness of the vests varied widely — some successfully deflected bullets and saved lives but others were poorly made and resulted in tragedy for the soldiers . In any case the vests were abandoned by many soldiers due to their weight on long marches as well as the stigma they got for being cowards from their fellow troops . At the start of World War I in 1914 , thousands of the French Cuirassier s rode out to engage the German Cavalry who likewise used helmets and armor . By that period , the shiny armor plate was covered in dark paint and a canvas wrap covered their elaborate Napoleonic - style helmets . Their armor was meant to protect only against saber s and light lance s . The cavalry had to beware of high velocity rifle s and machine gun s like the foot soldiers , who at least had a trench to protect them . Modern armor . Soldiers use metal or ceramic plates in their battledress , providing additional protection from rifle rounds . Metallic components or tightly - woven fiber layers can give soft armor resistance to stab and slash attacks from a knife . Mail armor continues to be used as protection against stab / slash attacks . Fibers . Kevlar is well known as a component of some bullet resistant vest s and bullet resistant face mask s . The PASGT helmet and vest used by United States military forces since the early 1980s both have Kevlar as a key component , as do their replacements . Other military uses include bullet resistant facemasks used by sentries . Civilian applications include Kevlar reinforced clothing for motorcycle riders to protect against abrasion injuries . Kevlar in non - woven long strand form is used inside an outer protective cover to form chaps that loggers use while operating a chainsaw . If the moving chain contacts and tears through the outer cover , the long fibers of Kevlar tangle , clog , and stop the chain from moving as they get drawn into the workings of the drive mechanism of the saw . Kevlar is used also in Emergency Service ' s protection gear if it involves high heat ( e . g . , tackling a fire ) , and Kevlar such as vests for police officers , security , and SWAT . The latest Kevlar material that DuPont has developed is Kevlar XP . In comparison with ' normal ' Kevlar , Kevlar XP is more light - weight and more comfortable to wear , as it is quilt stitch is not required for the ballistic package . Another fiber used to manufacture a bullet resistant vest is Dyneema . Originated in the Netherlands , Dyneema has an extremely high strength - to - weight ratio ( a 1 - mm - diameter rope of Dyneema can bear up to a 240 - kg load ) , is light enough that it can float on water , and has high energy absorption characteristics . Dyneema is a polyethylene fiber . Protected areas . Shield . A shield is held in the hand or arm . Its purpose is to intercept attacks , either by stopping projectiles such as arrows or by glancing a blow to the side of the shield - user . Shields where also used offensively as a bludgeoning weapon . Shields vary greatly in size , ranging from large shields that protect the user ' s entire body to small shields that are mostly for use in hand - to - hand combat . Shields also vary a great deal in thickness ; whereas some shields were made of thick wooden planking , to protect soldiers from spears and crossbow bolts , other shields were thinner and designed mainly for glancing blows away ( such as a sword blow ) . In prehistory , shields were made of wood , animal hide , or wicker . In antiquity and in the Middle Ages , shields were used by foot soldiers and mounted soldiers . Even after the invention of gunpowder and firearms , shields continued to be used . In the 18th century , Scottish clans continued to use small shields , and in the 19th century , some non - industrialized peoples continued to use shields . In the 20th and 21st century , shields are used by military and police units that specialize in anti - terrorist action , hostage rescue , and siege - breaching . Head . A combat helmet is among the oldest forms of personal protective equipment , and is known to have been worn by the Assyrians around 900 BC , followed by the ancient Greeks and Romans , throughout the Middle Ages , and up to the end of the 17th century by many combatants . Their materials and construction became more advanced as weapons became more and more powerful . Initially constructed from leather and brass , and then bronze and iron during the Bronze and Iron Ages , they soon came to be made entirely from forged steel in many societies after about 950 AD . At that time , they were purely military equipment , protecting the head from cutting blows with sword s , flying arrow s , and low - velocity musket ry . Many medieval helmets rested on the shoulders and prevented the wearer from turning his or her head , greatly restricting mobility . During the 18th and 19th centuries , helmets were not widely used in warfare , instead many armies used non - armored hats that offered no protection against blade or bullet . The arrival of World War I , with its trench warfare and wide use of artillery , led to mass adoption of metal helmets once again , this time with a shape that offered mobility , a low profile , and compatibility with gas masks . Today ' s militaries often use high - quality helmets made of ballistic materials such as Kevlar and Aramid , which have excellent bullet and fragmentation stopping power . Some helmets also have good non - ballistic protective qualities , though many do not . The two most popular ballistic helmet models are the PASGT and the MICH . The Modular Integrated Communications Helmet ( MICH ) type helmet has a slightly smaller coverage at the sides which allows tactical headsets and other communication equipment . The MICH model has standard pad suspension and four - point chinstrap . The Personal Armor System for Ground Troops ( PASGT ) helmet has been in use since 1983 and has slowly been replaced by the MICH helmet . A ballistic face mask is designed to protect the wearer from ballistic threats . Ballistic face masks are usually made of kevlar or other bullet - resistant materials and the inside of the mask may be padded for shock absorption , depending on the design . Due to weight restrictions , protection levels range only up to NIJ Level IIIA . Torso . A ballistic vest helps absorb the impact from firearm - fired projectile s and shrapnel from explosions , and is worn on the torso . Soft vests are made from many layers of woven or laminated fibers and can be capable of protecting the wearer from small caliber handgun and shotgun projectiles , and small fragments from explosives such as hand grenade s . Metal or ceramic plates can be used with a soft vest , providing additional protection from rifle rounds , and metallic components or tightly - woven fiber layers can give soft armor resistance to stab and slash attacks from a knife . Soft vests are commonly worn by police forces , private citizens and private security guard s or bodyguards , whereas hard - plate reinforced vests are mainly worn by combat soldiers , police tactical units and hostage rescue teams . A modern equivalent may combine a ballistic vest with other items of protective clothing , such as a combat helmet . Vests intended for police and military use may also include ballistic shoulder and side protection armor components , and explosive ordnance disposal technicians wear heavy armor and helmets with face visors and spine protection . Limbs . Medieval armor often offered protection for all of the limbs , including metal boots for the lower legs , gauntlets for the hands and wrists , and greaves for the legs . Today , protection of limbs from bombs is provided by a bombsuit . Most modern soldiers sacrifice limb protection for mobility , since armor thick enough to stop bullets would greatly inhibit movement of the arms and legs . Performance standards . Due to the various different types of projectile , it is often inaccurate to refer to a particular product as " bulletproof " because this implies that it will protect against any and all threats . Instead , the term bullet resistant is generally preferred . The standards are regional . Around the world ammunition varies and as a result the armor testing must reflect the threats found locally . According to statistics from the National Law Enforcement Officers Memorial Fund , a law enforcement officer ’ s job is extremely dangerous with one officer being killed every 53 hours in the line of duty . Even more astounding is that this number is on the rise . In 2011 , 173 officers were killed , with 68 of them being killed due to a gun - related incident . As a result each law enforcement agency or para - military organizations will have their own standard for armor performance if only to ensure that their armor protects them from their own weapon . While many standards exist a few standards are widely used as models . The US National Institute of Justice ballistic and stab documents are examples of broadly accepted standards . Since the time that NIJ started testing , the lives of more than 3 , 000 officers were saved . In addition to the NIJ , the United Kingdom ' s Home Office Scientific Development Branch ( HOSDB — formerly the Police Scientific Development Branch ( PSDB ) ) standards are also used by a number of other countries and organizations . These " model " standards are usually adapted by other countries by incorporation of the basic test methodologies with modification of the bullets that are required for test . NIJ Standard - 0101 . 06 has specific performance standards for bullet resistant vests used by law enforcement . This rates vests on the following scale against penetration and also blunt trauma protection ( deformation ) : In addition to the NIJ and HOSDB standards , other important standards include : the German Police ' s Technische Richtlinie ( TR ) Ballistische Schutzwesten , Draft ISO prEN ISO 14876 , and Underwriters Laboratories ( UL Standard 752 ) . Textile armor is tested for both penetration resistance by bullets and for the impact energy transmitted to the wearer . The " backface signature " or transmitted impact energy is measured by shooting armor mounted in front of a backing material , typically oil - based modelling clay . The clay is used at a controlled temperature and verified for impact flow before testing . After the armor is impacted with the test bullet the vest is removed from the clay and the depth of the indentation in the clay is measured . The backface signature allowed by different test standards can be difficult to compare . Both the clay materials and the bullets used for the test are not common . In general the British , German and other European standards allow 20 – 25 mm of backface signature , while the US - NIJ standards allow for 44 mm , which can potentially cause internal injury . The allowable backface signature for this has been controversial from its introduction in the first NIJ test standard and the debate as to the relative importance of penetration - resistance vs . backface signature continues in the medical and testing communities . In general a vest ' s textile material temporarily degrades when wet . Neutral water at room temp does not affect para - aramid or UHMWPE but acidic , basic and some other solutions can permanently reduce para - aramid fiber tensile strength . ( As a result of this , the major test standards call for wet testing of textile armor . ) Mechanisms for this wet loss of performance are not known . Vests that will be tested after ISO - type water immersion tend to have heat - sealed enclosures and those that are tested under NIJ - type water spray methods tend to have water - resistant enclosures . From 2003 to 2005 , a large study of the environmental degradation of Zylon armor was undertaken by the US - NIJ . This concluded that water , long - term use , and temperature exposure significantly affect tensile strength and the ballistic performance of PBO or Zylon fiber . This NIJ study on vests returned from the field demonstrated that environmental effects on Zylon resulted in ballistic failures under standard test conditions . Ballistic testing V50 and V0 . Measuring the ballistic performance of armor is based on determining the kinetic energy of a bullet at impact . Because the energy of a bullet is a key factor in its penetrating capacity , velocity is used as the primary independent variable in ballistic testing . For most users the key measurement is the velocity at which no bullets will penetrate the armor . Measuring this zero penetration velocity ( V0 ) must take into account variability in armor performance and test variability . Ballistic testing has a number of sources of variability : the armor , test backing materials , bullet , casing , powder , primer and the gun barrel , to name a few . Variability reduces the predictive power of a determination of V0 . If for example , the V0 of an armor design is measured to be with a 9 mm FMJ bullet based on 30 shots , the test is only an estimate of the real V0 of this armor . The problem is variability . If the V0 is tested again with a second group of 30 shots on the same vest design , the result will not be identical . Only a single low velocity penetrating shot is required to reduce the V0 value . The more shots made the lower the V0 will go . In terms of statistics , the zero penetration velocity is the tail end of the distribution curve . If the variability is known and the standard deviation can be calculated , one can rigorously set the V0 at a confidence interval . Test Standards now define how many shots must be used to estimate a V0 for the armor certification . This procedure defines a confidence interval of an estimate of V0 . ( See " NIJ and HOSDB test methods " . ) V0 is difficult to measure , so a second concept has been developed in ballistic testing called V50 . This is the velocity at which 50 percent of the shots go through and 50 percent are stopped by the armor . US military standards define a commonly used procedure for this test . The goal is to get three shots that penetrate that are slower than a second group of three shots that are stopped by the armor . These three high stops and three low penetrations can then be used to calculate a V50 velocity . In practice this measurement of V50 requires 1 – 2 vest panels and 10 – 20 shots . A very useful concept in armor testing is the offset velocity between the V0 and V50 . If this offset has been measured for an armor design , then V50 data can be used to measure and estimate changes in V0 . For vest manufacturing , field evaluation and life testing both V0 and V50 are used . However , as a result of the simplicity of making V50 measurements , this method is more important for control of armor after certification . Cunniff analysis . Using dimensionless analysis , Cuniff arrived at a relation connecting the V and the system parameters for textile - based body armors . Under the assumption that the energy of impact is dissipated in breaking the yarn , it was shown that Here , Military testing . After the Vietnam War , military planners developed a concept of “ Casualty Reduction ” . The large body of casualty data made clear that in a combat situation , fragments , not bullets , were the greatest threat to soldiers . After WWII vests were being developed and fragment testing was in its early stages . Artillery shells , mortar shells , aerial bombs , grenades , and antipersonnel mines are all fragmentation devices . They all contain a steel casing that is designed to burst into small steel fragments or shrapnel , when their explosive core detonates . After considerable effort measuring fragment size distribution from various NATO and Soviet bloc munitions , a fragment test was developed . Fragment simulators were designed and the most common shape is a Right Circular Cylinder or RCC simulator . This shape has a length equal to its diameter . These RCC Fragment Simulation Projectiles ( FSPs ) are tested as a group . The test series most often includes 2 grain ( 0 . 13 g ) , 4 grain ( 0 . 263 g ) , 16 grain ( 1 . 0 g ) , and 64 grain ( 4 . 2 g ) mass RCC FSP testing . The 2 - 4 - 16 - 64 series is based on the measured fragment size distributions . The second part of “ Casualty Reduction ” strategy is a study of velocity distributions of fragments from munitions . Warhead explosives have blast speeds of to . As a result they are capable of ejecting fragments at very high speeds of over 1000 m / s ( 3330 ft / s ) , implying very high energy ( where the energy of a fragment is ½ mass × velocity , neglecting rotational energy ) . The military engineering data showed that like the fragment size the fragment velocities had characteristic distributions . It is possible to segment the fragment output from a warhead into velocity groups . For example 95 % of all fragments from a bomb blast under have a velocity of or less . This established a set of goals for military ballistic vest design . The random nature of fragmentation required the military vest specification to trade off mass vs . ballistic - benefit . Hard vehicle armor is capable of stopping all fragments , but military personnel can only carry a limited amount of gear and equipment , so the weight of the vest is a limiting factor in vest fragment protection . The 2 - 4 - 16 - 64 grain series at limited velocity can be stopped by an all - textile vest of approximately 5 . 4 kg / m ( 1 . 1 lb / ft ) . In contrast to the design of vest for deformable lead bullets , fragments do not change shape ; they are steel and can not be deformed by textile materials . The FSP ( the smallest fragment projectile commonly used in testing ) is about the size of a grain of rice ; such small fast moving fragments can potentially slip through the vest , moving between yarns . As a result fabrics optimized for fragment protection are tightly woven , although these fabrics are not as effective at stopping lead bullets . In practice . In December 2009 , during the War in Afghanistan , a British soldier deployed in southern Helmand Province , survived a shot to the back during an operation to clear insurgents from a village , protected by the body armor kit he was wearing .