"One of the downsides of using a small strobe is that you don't get the nice modeling light like the big studio guns.
That means that you have to pre-visualize your light. If you are new to strobes this may not be trivial even on a bare strobe, but throw some modifiers in (e.g. a softbox or an umbrella) and it get even harder. This is why a modeling light is can be your best friend as you make your first steps into the modifiers world. In this tutorial I will explain how you can add a modeling light to a strobe using a DIY Double Flash Bracket, but any double flash bracket will do."
Via Philippe Gassmann