Standalone 3+ will stop 5.56 green tip, 308 etc. Meaning it does not need any other ballistic material behind plate to achieve this rating.
This plate is also designed to achieve NIJ Level IV protection when worn “In-Conjunction” with a NIJ certified Level IIIA panel. ”In-conjunction” plates are designed to stop the specified threat within the vest/plate matrix. Some fragments may penetrate the plate, but are of much reduced energy easily stopped by the ballistic vest worn underneath.
NIJ Threat Level IV Hard Armor Plates – Rifle Plates are designed to defeat one round of .3006 Armor Piercing (AP) at 868 meters/sec and lesser threats.