The Small Arms Protective Insert (SAPI) is a ceramic trauma plate used by the United States Armed Forces.The Kevlar Interceptor vest itself is designed to stop projectiles up to and including 9×19mm Parabellum submachine gun rounds, in addition to fragmentation. To protect against higher-velocity rifle rounds, SAPI plates are needed.
- Ballistic material: HDPE (Polyethylene thermoplastic made from petroleum).
- Protection level is III according to NIJ interim requirements.
Bullet proof vests are designed to ‘trap’ and slow bullets down as they attempt to pass through the vest. Bullet Proof Vests come in two different types; hard and soft. The ‘soft’ armors are designed to protect against most handgun and small arms ammunition, whereas ‘hard’ armors are designed to stop high caliber and armor piercing rounds.
The NIJ classifies all armors in the following levels:
|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|
|.30 Armour Piercing (M2 AP)||x|
- Size: 300×250 mm ± 5. = 10X12 inch
- Thickness: 20mm ± 2. = 1 inch
- Weight: ±1450 gr. = 3 pounds and 3.15 ounces
HDPE is known for its large strength-to-density ratio.The density of HDPE can range from 0.93 to 0.97 g/cm3 or 970 kg/m3. Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength than LDPE. The difference in strength exceeds the difference in density, giving HDPE a higher specific strength. It is also harder and more opaque and can withstand somewhat higher temperatures (120 °C/ 248 °F for short periods). High-density polyethylene, unlike polypropylene, cannot withstand normally required autoclaving conditions.