This is a custom PCB with 16 LEDs and a 10F202 Microchip. The LEDs are in 4 sets of 4 and each set flashes in a rotating pattern. Board fits sandwiched in between some modified LEGO tiles which are glued together. If you are interested in this, please contact me through email at info@brickmodder.net. For more information on custom electronics for LEGO and other scale models please visit www.brickmodder.net and www.lifelites.com