Continuity mistake: When Jack, Stark, and Allison walk into the room at G.D. where Martha escaped from Stark is seen putting his hands on his hips twice.
Continuity mistake: When Jack is using the mustard to find Martha, Vincent ducks behind the counter. The shot changes to show just Vincent and he is shown ducking down again.
Chosen answer: It's basically just a type of suit that's made for whatever special project they're working on. No different than a lab coat, hazmat suit, fire coat, etc.