NIJ and CAST Body Armour Levels and Standards

 

Bulletproof vests are tested and standardised according to the ammunition they can protect against. This is why vests are referred to according to their level, which is set by the relevant testing agency. For example, in the US the National Institute of Justice (NIJ) is responsible for approving body armour and is widely considered to be the world leader in testing and grading bulletproof vests. The respective institution in the UK is the Home Office’s Centre for Applied Science and Technology (CAST, formerly HOSDB), which is considered to be the world leader in testing and grading stab and spike-proof vests. However, these institutions often share testing methods and equipment, so armour that meets the standards of one will meet the standards of its equivalent.

NIJ LEVELS

The NIJ levels for bulletproof armour outline the various strengths and sizes of ammunition that a bulletproof vest can protect against. The higher the level, the stronger the threat it can protect against, and each level is capable of stopping lower-level attacks. For example, A Level III vest will protect against ammunition outlined in every preceding level. These levels are as follows: 

		NIJ Level IIa	NIJ Level II	NIJ Level IIIa	NIJ Level III	NIJ Level IV
	Areal Density	3.5 kg/m	4.2 kg/m	5.9 kg/m	25.9 kg/m	32.5 kg/m
	Thickness	4mm	5mm	6mm	15mm	20mm
.9mm		x	x	x	x	x
.44 Magnum				x	x	x
5.56mm					x	x
7.62mm NATO					x	x
.30 Armour Piercing (M2 AP)						x

 

CAST LEVELS

CAST levels cover stab and spikeproof vests, both of which require additional protection than a bulletproof vest. As mentioned above, CAST is considered to be the world leader in stab and spike testing, but equivalent institutions may meet the same standards. The levels of protection offered by stab-proof vests are as follows:

	KR1		KR2
	Knife Resistant Level 1		Knife Resistant Level 2
Energy Level	E1	E2	E1	E2
Energy (joules)	24	36	33	50
Velocity	5 m/sec	6.2 m/sec	5.9 m/sec	7.3 m/sec
Total Missile Mass	1.9 kg	1.9 kg	1.9 kg	1.9 kg
Maximum Penetration	7mm	20mm	7mm	20mm

 

Of course, spike-proof vests are not always the same as stab-proof vests, and may require additional protection. They are tested and graded just as all body armour is, and it is important when choosing a vest to make sure that it meets the appropriate testing. Spike protection testing was first introduced to address the threat faced by Prison Officers, and the levels are as follows: 

	KR1 & SP1		KR2 & SP2
	Knife Resistant Level 1 & Spike Protection Level 1		Knife Resistant Level 2 & Spike Protection Level 2
Energy Level	E1	E2	E1	E2
Energy (joules)	24	N/A	33	N/A
Velocity	5.0 m/sec	N/A	5.9 m/sec	N/A
Total Missile Mass	1.9 kg	N/A	1.9 kg	N/A
Maximum Penetration	KR1=7mm, SP1=0mm	N/A	KR2=7mm, SP2=0mm	N/A

Body armour must meet the appropriate levels of protection as outlined by the relevant institution. If it does not, it may not offer you the correct protection.