Construction:
Protective vests are made of various types of material and constructed in different ways.
There are two main types of guards: hard and soft ballistic body amour.
In many cases, a combination of both methods is needed to reach certain levels of protection.
A soft ballistic vest may provide the all-round protection required to meet German protection class 1 SK standards.
Hard ballistic front and back inserts guarantee German protection class SK 4.
Most protective vests are constructed in this way.
The hard ballistic plates will only reach full protection when worn in combination with soft ballistic body armour. Protective vest vary not only in protective function but also in which body parts are protected. Most protective vests only shield the largest target areas of the body, usually the torso. Different types of body armour use additional guards to provide extra protection to certain body parts such as the genital area, shoulders, neck, arms and legs. The challenge is to balance extra protection with freedom of movement. Other differences are explained by the construction of the body armour. Ballistic protection inserts are sewn into the protective vest liner of highly durable fabric which allows wearing armour close to the body and preventing damage from every day wear and tear. This fabric may also offer attachment points for additional gear or allow for covert wear, for example by matching the colour of outer clothing.

Soft Ballistic Armour
Bullets hit a mesh or foil structure made up of several layers of tear-resistant fabric. Bullets penetrating the individual layers will destroy or stretch layers and lose energy. Once, a bullet has passed through several layers, all its kinetic energy will have been lost and the bullet gets stuck. Protective vests made out of silk were first used as body armour when firearms came on the market. Today, the most frequently used material is aramide fibre known by trade names such as Twaron or Kevlar. Other materials including Dyneema are also used. Although these fibres are extremely tear-resistant they do tend to become less resistant over time. This is an aging process which acts on the material over a period of several years and which is accelerated by the impact of UV-light. Moisture may also compromise these properties. This is why soft ballistic protective inserts of protective vests are sealed inside plastic material. With a sufficient number of layers, any bullet can be stopped in theory. In practice, soft ballistic inserts are only made for protection from pistol calibers. They are less appropriate for rifle bullets as they would require extremely heavy armour in order to stop the kinetic energy which is much higher compared to pistol bullets. This is due to their pointy shape, greater propelling charge and longer barrels of rifles. In this case, hard ballistic inserts are used.


Hard Ballistic Armour
Bullets hit a hard plate dispersing its kinetic energy. The plate absorbs the kinetic energy and changes shape. This concept has been applied to body armour for a long time. For centuries, metals (ballistic steel) have been used for this purpose. Today, oxide ceramics or polyethylene plates are also used. Modern hard ballistic protection plates are made of a combination of various materials that are layered and curved for better impact absorption and for an improved fit to the body of the user. Theoretically, protective plates can stop any bullet depending on the thickness of the material. For reasons discussed above, most protective plates will reach their maximum protection potential only in combination with soft ballistic armour. The US military is the largest buyer of hard ballistic body armour plates and has set certain design standards. Most plates measure 10x12 inches with slanted upper corners and are called (E)SAPI ((Enhanced) Small Arms Protective Insert) plates. Other shapes of plates are also manufactured. For a long time it was thought that hard ballistic materials could not offer full protection as the weight of protective inserts would not allow for practical use of such body armour. Purely hard ballistic protective vest were therefore made solely in form of so-called plate carriers. Here, only the front and back is protected by so-called stand alone plates. These special plates can stop bullets even without soft ballistic liner armour, but they are heavier.

Puncture Protection
Note that stabbing weapons have a different impact than bullets. They may cut, displace or punch. Lightweight protective fabrics may be sufficient to prevent injury from a long knife cut (not in all cases). A needle puncture will, however, penetrate a soft ballistic protective vest. Lightweight protective vests are fitted with additional inserts of metal foil or interlaced metal rings to provide sufficient puncture protection. These foils are especially effective in guarding against objects with punching action, e.g. needles or canula from syringes. The interlaced metal rings are similar to chainmail armour and protect against the displacement impact of knife blades or even axes. Vests of German protection class SK 3 and 4 with hard ballistic protective inserts offer puncture protection. Such armour systems usually cover the front and back area only, so that additional puncture guards may be required for the lateral parts of the body. The methods described above may be used for this purpose.