PDS6-M2A "Interceptor"

The PDS6-M2A (Personal Defense System, 6th version - 2nd Model, A variant), named Interceptor is an ultra-high strength body armor developed by Gaia Defense Systems on Dragonia. It is an armored rig that is built for and exclusively uses Dragon Steel plates. The armor is on the heavier side but the amount of protection it offers is unmatched by any other armor system used by anyone in Squad Mates. This armor has been rated to have survived 46 5.56x45mm GSS round in one test with over 20 of those being in the same spot. It is prohibitively expensive, coming in at about 323,000 Credits for 1 unit, complete with the 4 Dragon Steel plates.

In terms of Squad Mates, you're better off shooting someone who's wearing this in the head.