Answering the requests of hobbyists our engineers designed an adjustable strobe. You can now control the rate of speed of the strobes. One of the adjustable strobes uses an alternating strobing of two lights, all at the rate of speed you choose. These strobe boards have the incandescent bulbs attached. Choose the color for your scene. PC Board measures 1 3/8″ X 1/2″ X 1/8″. Operate on 9-14 volts AC/DC.