Design the Dark modifies apparel to allow lights to be added and interchangeable. (Lights & Battery packs not included) Your typical light up jacket is sewn directly onto the jacket which, in time, will wear out the light and will need to be replaced by sending it back to the supplier. For the jackets, the battery packs with the button to turn on the lights is located in the pockets and have 4 modes: ON, Slow Flash, Quick Flash, and OFF. With our apparel, you simply replace the light by following the custom tubing system which conforms the light into your specific design. Purchasing more lights will give you the ability to match the color light to your clothing, your accessories, or even your mood. Jacket is not created by us just modified to allow light design.