Small Arms Protective Insert

From Wikipedia, the free encyclopedia

The Small Arms Protective Insert (SAPI) is a ceramic trauma plate used by the United States Armed Forces. It was first used in the Interceptor Body Armor, a ballistic vest. It is now also used in the Improved Outer Tactical Vest as well as the Modular Tactical Vest, in addition to commercially available “plate carriers”. 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.


In May 2005, the U.S. Armed Forces began replacing the standard Small Arms Protective Insert plates with the Enhanced Small Arms Protective Insert (ESAPI). An ESAPI provides protection from .30-06 Spring field M2 armor-piercing (AP) with a steel penetrator in accordance with the NIJ Level IV standard, but costs about $600 per plate, 50% more than SAPI plates. They are produced by CeradyneBAE Systems, and ArmorWorks Enterprises.

Materials and capabilities

The standard plate for the Interceptor body armor is made of boron carbide or silicon carbide ceramic. New ESAPI plates are also made of boron carbide. The standard plates are not given an NIJ rating, as they are tested in accordance with specific protocols for the military and not the NIJ’s testing. Military testing calls for survivability of three hits from the round marked on the plate – for standard SAPI, of a caliber up to 7.62×51mm NATO M80 ball and of a muzzle velocity up to 2,750 ft/s (840 m/s). For ESAPI, a .30-06 Spring field M2 armor-piercing (AP) (.30-06 black-tip armor-piercing) cartridge. This performance is only assured when backed by the soft armor of the OTV (or any soft armor which meets military requirements for protection). The ceramic plate is backed with a shield made of Spectra, a material up to 40% stronger than Kevlar, to trap any fragments of either plate or projectile and prevent them from injuring the wearer.

Sizes and weights

SAPI plates meant for body armor come in front and back plates which are identical, and smaller side plates. The front and back plates come in five sizes. Their dimensions are the following:

Front and back SAPI plates:

ESAPI plates are the same size but slightly greater in weight.

Side SAPI (SSAPI) torso side plates, and their replacement, the Enhanced Side Ballistic Inserts (ESBI), have identical weights and dimensions. ESBI plates can be replaced with size X-Small ESAPI plates (by unfolding an extension built into the bottom of the ESBI Carrier assembly), if permitted by the unit commander.

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