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Stab Vest (Stab Proof Vest) Protection Levels

Home Office Scientific Development Branch (HOSDB)

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Stab Vest Test Knife. This is a photograph of the original Sheffield Steel L113 Police Test Blade.

Left: Photo of the original Stab Vest test knife as used in the 1993 Knife Resistance testing of Police Body Armour. This is a Six Inch Bowie Type made from high grade Sheffield Steel.

Police confiscated knives and improvised stabbing weapons are used as a basis for body armour stab vest test procedures.

Knives that pose the most serious threat to body armour systems are termed “engineered”. This in Plain English means a blade type that when “fully impacted” into a wooden block, would retain its shape and pointed effectiveness to be capable of being used again in its original, relatively undamaged state.

If you were to examine most kitchen knives, you might  determine that such “drawer knives” do not really qualify for inclusion. Fully impacting a bread knife into a wooden surface would probably snap the blade. In fact, most household knifes will bend if presented with any degree of force. The instant a Knife starts to bend is the physical energy point where the pointed knife weapon looses its penetration potential.

In contrast to the above, knives purchased from specialist shops are quite different - they are made of high grade steel and drop into the “engineered” category. They are capable of retaining their shape at maximum human impact energy. Such blade types are what body armour systems must resist to qualify for certification. The newest test blade in the UK 2007 Police standard is just such a blade - with a pin sharp tip, and virtually “no give” in its construction.

The Spike Test  is considerably more severe than the knife test. Materials capable of preventing knives penetrating will often completely fail to stop pointed weapons of relatively small diameter.

BODY ARMOUR UK - Stab Protection Levels Table

This table relates to the current HOSDB 2007 (UK Police - “Home Office Scientific Development Branch” Standard). The Anti-Stab “Yellow Row” is produced in accordance with the PSDB 1993 Stab Standard

UK Stab HOSDB Protection Levels

Stab Level found in our  Product Codes Ending

Impact Energy
Strike 1

Impact Energy
Strike 2

Protection
Level

UK Police
Test Weapon

Joules

Penetration
Max (mm)

Joules

Penetration
Max (mm)

Anti-Stab

3 Inch Bowie Knife (L113)

-NAS

25

5

Impacts at Energy 1 Strike + 50% (Energy Strike 2) were not introduced until 1999

6 Inch Bowie Knife (L104)

KR1+SP1

Engineered Blade (P1/B)

-SP1

24

7

36

20

Engineered Spike (SP/B)

Nil

Nil

KR2+SP2

Engineered Blade (P1/B)

-SP2

33

7

50

20

Engineered Spike (SP/B)

Nil

Nil

KR3+SP3

Engineered Blade (P1/B)

-M39

43

7

65

20

Engineered Spike (SP/B)

Nil

Nil

Anti-Stab Vests, Protection from most Knife Threats

This protection level is made in accordance with the PSDB (1993) stab procedure to a 25 Joule energy strike. We call it Anti-Stab to avoid any confusion when comparing it with our newer standards. To call the vest KR25 might give the impression that it is more capable than KR1+SP1 (24 Joule). The 1993 stab standard was revised in 1999, and again in 2003. Prior to 1999 we called this a KR25
The Anti-Stab protection level protects from most stab threats from larger cross-sectional blades. The test blades for this system are shown above right, and represent typical high quality engineered knives that might be used by an assailant. The 1993 standard was the first knife standard introduced in the UK.
The Anti-Stab system protects from knife attack, slashes, broken bottles and the trauma from physical assault.
Protection systems made in the Anti-Stab standard are considerably less expensive than our newer systems listed below and offer excellent protection from bladed weapons.

Stab Vest Test Knives. The larger knife has a six inch blade. The smaller weapon has a 3 inch blade

For most general security duties the Anti-Stab level provides excellent protection. It will resist the type of weapons shown above - The L113 & L104 (PSDB 1993) Test Blades.

Contrary to popular belief - the bigger the knife, the easier it is for body armour to resist its penetration. This is the reason our newest  protection materials concentrate on smaller cross-sectional weapons.

We make our anti stab vest body armour from the same material as our bomb blast blankets. In January 2006 we re-tested the vest to reveal a very impressive V50 result of 400m/s, which is a steel fragment strike at a supersonic velocity. Personnel who remove land mines are generally supplied with 460m/s systems.

We also ran some low threat ballistic trials against this anti-stab body armour. We reported a .38 Special at 200m/s and a .45 Colt at 180m/s.
Whilst the above is better than nothing, it is not good enough for us to report any credible claim to a ballistic vest. The V50 of 400 m/s  however is exceptionally good in a World where terrorism is a constant concern to us all. Fragmentation levels of 240m/s are used in police bomb search visors. Face visors capable of stopping handgun bullets are rated at 600m/s


KR1+SP1 - Protects against - Knives, Slashing, Spiked Weapons & Hypodermic Syringes

A 2007 Police Standard to protect from pointed weapons and knives. KR signifies "Knife resistance" and SP indicates "Spike Resistance". The picture below (left) shows both test weapons. The spike can be compared to "Ice Pick" or any weapon ground to a point. The material we use to produce our SP systems are also impermeable to attack from hypodermic syringes.
The system offers superb protection to all edged, pointed and sharp weapon attacks. The armour system is constructed of multi-layered flexible fabric and contains no solid plates. It can be combined with our HG1/A, HG1 and HG2 ballistic armours to offer dual purpose protection. Spike resistant armours have become necessary due to evolutionary threats from assailants armed with improvised pointed weapons and syringes. Syringes are becoming an increasing menace. Many enquiries we receive are more concerned with syringes than a threat from a knife. The threat of AIDS and Hepatitis are well documented, less well known is that an air bubble injected into the bloodstream from an empty syringe can result in near instant fatality.

Photo of the P1/B Test Blade & Spike

Shown left are the 2007 Police Test Weapons. The Spike is easily capable of penetrating most current issue police stab armour in levels KR1, KR2 & KR3 at the 24 Joule strike level.
The Blade shown left is a modified sharper version of the 1999 blade. It is worth noting that a 2007 spec KR1 is quite superior to a 1999 KR1.

Below is the P1/B Engineered Blade tip shown against a fingertip.

Right - typipical hypodermic syringe - easily stopped by our SP rated systems.

HOSDB P1/B Stab Test Blade shown against a finger tip
Hypodermic Syringes will simply bend if stabbed into our KR1+SP1 knife resistant body armour

KR2+SP2 - Protects against - Knives, Slashing, Spiked Weapons & Hypodermic Syringes in a high risk environment

Syringes can not be stopped by many stab vests. KR1+SP1  easily prevents the penetration of pointed weapons

Using the same material system as the KR1+SP1 with an increased resistance of 33 Joules against a P1/B blade and a spike. This level of protection is better suited to our overt styles of armour because of increased thickness and reduced flexibility.
The level is suited to occupational risks which are greater than occasional. Confrontations on a regular basis in high crime areas might warrant this specification - example Police "Stop and Search" duties in districts with a known weapons carrying culture.
For a general purpose stab / syringe vest, KR1+SP1 is generally preferable.

KR3+SP3 - Protects against - Knives, Slashing, Spiked Weapons & Hypodermic Syringes in an extreme risk environment

Requests for this specification are virtually nil compared to the above three protection levels. The KR3+SP3 is generally purchased in overt styles for a very specific purpose. It is the type of item that a police station might hold in small quantities to deal with situations of disarming with reasonable advance notice
The KR3+SP3 specification is usually purchased with the intention of occasional use in a potentially life threatening situation. Risk assessments recommending this protection level are relatively rare. Our sales of this level are less than all our other protection levels combined. Manufacturing KR3+SP3 systems from specialty fabrics usually results in good ballistic properties - for this reason we decided to make our KR3+SP3 fully ballistic (bullet resistant) to HG2/KR3+SP3 for economic reasons.

How to relate stab proof resistance with a “real world” example

How much is a Joule of impact energy in a “real world” example that can be easily understood. You can choose any everyday object and drop it from a given height to calculate the Joules of impact energy.
In this example we will compare a real test sabot (shown left) and a 2 litre bottle of water. Both have similar weights and diameters.

An Official Stab Test Sabot. The full assembly is dropped onto sample stab vest

On the left is the stab test assembly used to strike a sample of body armour. The entire article is placed inside the equivalent of a “plastic drainpipe”, and allowed to drop (gravity free-fall) onto the body armour test sample.

The speed of the stab test sabot is measured at “just before” point of impact and the Joules of energy calculated from the known mass and velocity. The mass of the stab vest test sabot fully assembled is 1.9 Kilograms

Spike testing is conducted in the same sabot (plastic assembly). The metal portion is exchanged for a metal spike holding arrangement.

Right: Something to compare with. This 2 litre bottle of drinking water (minus 1 wine glass full - 146 mls to be precise) is exactly the same weight and diameter as the test sabot. This comparison gives a clear idea of the “punch power” of a sample “stab proof vest” sample test strike.

Bottle Figure arrived at by adding the 46 gram water bottle to its 1854 ml water contents.

2 Litres of water - similar in weight and diameter to the HOSDB stab test sabot

Testing a Stab Vest - A Simple Explanation

Using the 2 litre bottle of water on the right we can produce this dedicated table of drop heights. If the bottle was raised to 4 feet 3 inches from the floor (gap between floor and bottle) and then dropped, it would release 24 Joules of energy upon striking the floor. This table should help your appreciation of the “punch power” of the stab-vest test sabot at different impact energy levels.

Stab Protection Level

Impact Energy at E1 Strike

Bottle Height in Feet & Inches (E1 Strike)

Impact Energy at E2 Strike

Bottle Height in Feet & Inches (E2 Strike E1+50%)

KR1+SP1

24

4’3”

36

6’4”

KR2+SP2

33

5’10”

50

8’10”

KR3+SP3

43

7’7”

65

11’5”

The weight of the Knife Test Sabot at 1.9 Kilograms with the P1/B test blade or spike fitted is sufficient to penetrate a human body and  possibly cause fatality without being dropped from any height - the actual weight alone is sufficient to penetrate human skin and tissue. This answers the obvious question of “how many Joules of stabbing energy can cause a fatality” - less than one.

Stab Vest Test Blade Type P1/B Drawing

Left: Image of the HOSDB P1/B Test Blade used to evaluate stab proof (resistant) body armour vests.
This test blade can also be seen in the plastic Test Sabot (above left).

Right: Drawing of SP/B Engineered Spike tip

Stab Vest Test using the SP/B Engineered Spike

A Final Word - There is no such thing as a Stab Proof Vest


The newspapers and media routinely refer to “stab proof vests” as a matter of course. The correct description is “stab resistant vests”, or simply a “stab vest”.

The word “proof” implies “convincing demonstration of irresistible stab properties” which can not truthfully be applied to any knife resistant safety product. The very fact that different stab protection levels are available is clear indication that the word “proof” suggests resistant to a defined level.


Stab Vest, Stab Vests, Stab Proof Vest and Stab Proof Vests are common terms for body armour with a defined level of resistance to a knife or pointed weapon. The same also applies to bullet proof vest terminology - bullet proof vests have a defined level of ballistic resistance.

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