The LED light in the center of the flower is powered by our unique Biological Battery. Our kit includes an LED, plastic flower, battery pack, biological medium, and everything else you need to assemble the kit. The LED can be left on for up to a few days. This kit is a part of our STEM Education Program. And it is for class or group use. We offer curriculum, training and supports for teachers for free. Minimum order of 25 is required. Thank you very much.