A Flash Suit was a suit worn by students competing in the Battle Rooms. Flash Suits were specially constructed to be mostly bind-free during normal use, but had special light sensors in the fabric that could tell if it had been "hit" by a Flash Pistol. When hit, a portion of the Flash Suit (or all of it, depending on where it was struck) would become immobile, or "frozen." A hit in one of the "vital" areas would cause the entire suit to become immobilized, including a clamp in the helmet that prevented the soldier from talking.
In a darkened room, undamaged portions of the suit emitted a slight glow, whereas damaged parts were completely dark. Flash Suits were different colors for each Battle School Army, and came in various sizes, although not "extremely small," as Julian "Bean" Delphiki found out.