Safe Light Vests are the newest and greatest life saving vests o the market. The vests meet and exceed the ANSI 107-2004 Class 2 and 3 spefications for refelctive safety vests. adding the lights has enhanced the visibility for at least a 1/4 mile vision in clear, fog or overcast conditions. The lights do not generate heat and are very lightweight. These water resistant vests can be worn in any extreme weather conditions. The lights are run by a battery pack with two double A batteries. Operationg the battery pack is done by manually pressing the button to turn lights on for a steady light or pressing button again for blinking light, pressing the bubtton the third time turns the device off. Remember that just because you're wearing a lighted safety vest, you must still be aware of traffic. It's your responsibility to make sure your out of the path of vehicles.