BALLISTIC RESISTANCE STANDARD
NIJ Level I (22 LR; 380 ACP)
This armor protects against .22 caliber Long Rifl e Lead Round Nose (LR LRN) bullets,with nominal masses of 2.6 g (40 gr) impacting at a minimum velocity of 320 m/s (1050 ft/ s) or less, and 380 ACP Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 6.2 g (95 gr) impacting at a minimum velocity of 312 m/s (1025 ft/s) or less.
NIJ Level IIA (9 mm; 40 S&W)
This armor protects against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 332 m/s (1090 ft/s) or less, and 40 S&W caliber Full Metal Jacketed (FMJ) bullets, with nominal masses of 11.7 g (180 gr) impacting at a minimum velocity of 312 m/s (1025 ft/s) or less.
NIJ Level II (9 mm; 357 Magnum)
This armor protects against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 358 m/s (1175 ft/s) or less, and 357 Magnum Jacketed Soft Point (JSP) bullets, with nominal masses of 10.2 g (158 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less.
NIJ Level IIIA (High Velocity 9 mm; 44 Magnum)
This armor protects against 9 mm Full Metal Jacketed Round Nose (FMJ RN) bullets, with nominal masses of 8.0 g (124 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less, and 44 Magnum Jacketed Hollow Point (JHP) bullets, with nominal masses of 15.6 g (240 gr) impacting at a minimum velocity of 427 m/s (1400 ft/s) or less.
NIJ Level III (Rifles)
This armor protects against 7.62 mm Full Metal Jacketed (FMJ) bullets (U.S. Military designation M80), with nominal masses of 9.6 g (148 gr) impacting at a minimum velocity of 838 m/s (2750 ft/s) or less. NIJ Level IV (Armor Piercing Rifl e) This armor protects against .30 caliber armor piercing (AP) bullets (U.S. Military designation M2 AP), with nominal masses of 10.8 g (166 gr) impacting at a minimum velocity of 869 m/s (2850 ft/s) or less.

STAB RESISTANCE STANDARD
The NIJ Standard 0115.00, ‘Stab Resistance of Body Armor’, has set two different protection classes and three protection levels in each class as the basis around which stab protective armor is to be engineered. The protection classes are defi ned as “Edged Blades” and “Spikes”. The protection levels are Level 1, Level 2 and Level 3.

The “Edged Blades” protection class has two test weapons: the S1 double edged engineered blade representative of large knives, and the P1 single edge engineered blade representative of typical small pocket knives. Both blades are manufactured from hardened steel with fl at ground cutting edges. The “Spike” protection class uses a 7-inch long hardened steel shaft of 0.163” diameter sharpened to a point. The test weapons are mounted in a specified 2 kg weight, ir sabot, which has a unique spring damping system designed to replicate the hand/wrist action during a stab attack. The mounted weapon is then dropped from various heights onto the armor, providing the required energy. The chart below shows the energy required and the allowable penetration for each weapon at the various threat levels.

The energies specifi ed in the three protection levels are the result of extensive research on actual attack energies using a cross section of the general population. Level 1 offers protection from 85% of likely attacks, Level 2 protects from 90%, and Level 3 protects from 96% of any attacks that a law enforcement.