These are studio strobes/flash set. It comes with a test button and variable dial for power setting from 1/8 to full. It also come with a 75 watts modeling lamp. These strobe flash work on any 110v power outlet. It will work as main light, back light or hair light and comes with a easy to use umbrella holder. You could easily adjust the shooting angle the strobe flash. The umbrellas will soften the light to give your images a professional look and get rid of the ugly shadows completely. This set works great with film or digital cameras and is ideal for in studio or on location shooting.