Also make sure that the manufacturer of ballistic plates has strict NIJ standards for ballistic protection. Most manufacturer will test plates and claim to be up to par with NIJ guidelines/standards and testing...
Ballistic Resistance of Body Armor NIJ Standard-0101.06 is a NIJ Standard that establishes minimum performance requirements and test methods for the ballistic resistance of personal body armor designed to protect the torso against gunfire. The standard is limited to ballistic resistance only and does not address resistance from knives or other sharply pointed objects. It reviews NIJ body armor classifications, details requirements (i.e., acceptance criteria, workmanship, armor backing material, and so forth), and discusses test methods (i.e., velocity measurement equipment, wet conditioning, test preparation, and so forth). This standard supersedes NIJ 2005 Interim Requirements, Ballistic Resistance of Body Armor (August 2005) and also supersedes NIJ Standard-0101.04 Rev. A, Ballistic Resistance of Personal Body Armor (June 2001).
On a side note, ESAPI plates are true stand alone plates even though they are rated at Level III protection. I would recommend Ceradyne plates if you can find them.
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