These like T-shirts are really crazy for the crazy guys.This T-shirt is showing that we are in digital world now.These digital clock T-shirts are powered by 4 x AAA batteries.Battery life is very low,lasting between 12-36 hours flash modes(digital clock or stop watch) selected and can be replaced.You can also switch-on and switch-off by a small button.The Battery box will also be removed when we have to wash it.