Tony Stark Light-Up Arc Reactor LED Iron Man 2 T Shirt, Black Black cotton t-shirt containing a light-up Arc Reactor. Powered by a battery pack cleverly hidden within an inside shirt pocket.Requires 4 AAA batteries (not included).With fresh batteries in the battery box, Arc Reactor will glow when switched on. Machine washable (all electrical components can be removed from the shirt). Please see the size chart as picture shown. Size M fits 5.2 ft~5.6 ft. Design by Teelight.