Your vest is only a level II or IIIA, think about it.
Ballistic vests are rated by the National Institute for Justice. These ratings give the wearer an idea of what the vest can stop. Here, Dorner is informing the police that their vests (with which he is familiar) are only capable of stopping handgun ammunition — Dorner is implying that he is armed with rifles which can penetrate police body armor.
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