A New World - S4-E2
Continuity mistake: At the end of the previous episode, when Jack comes home to find Tess there, Tess says "I thought you'd never get here" and then asks if he wants a drink and goes to the kitchen. In the beginning of this episode (which is suppose to be the same scene) she says "I thought you'd never get home" and Jack replies "you're not in Australia" and then Tess asks S.A.R.A.H. to make him lunch.
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.