From Orson Scott Card Wiki

Flash Suits, in conjunction with Flash Pistols (also known as "Daos"), made up a soldier's uniform in the Battle Room. 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 the "lethalness" of the hit) would become immobile, or "frozen." Another aspect of Flash Suits is their glow: in a darkened room, undamaged portions of the suit emit a slight glow, whereas damaged parts are completely dark. Flash Suits are different colors for each team, and come in various sizes, although not "extremely small," as Bean found out.