Build your own stop light sequencer with the Velleman 4 way LED Traffic Light Minikit. The kit mimics the same functions as a traffic light by cycling through the red, yellow and green LEDs. Perfect for your next light project, model train kit, or toy setup. Adjust the light changing speed to match your traffic's pace with the included potentiometer. The MK131 runs on a 9V battery (battery is not included) and uses the 9V battery holder as a stand to sit upright. Some soldering is required for this product.