Unlike the basic metal armor it strongly resembles, this armor is an actual pre-War military design, constructed from plans left behind by Nikola Tesla, confiscated by the US government after his death. It is designed to protect the wearer against energy attacks - three Tesla Attraction Coils disperse a large percent of directed attacks. However, since its protection against conventional firearms is comparable to the post-war metal armor, its popularity was limited, although some suits made their way to National Guard depots and from there to the wastes.
Tesla armor is normally the last armor obtained by the Vault Dweller in Fallout. It is almost exclusively designed for the final battle against the Master. Its extremely high DT for laser weapons (90%) renders the Master's laser to be almost harmless.