The Tool is one of the most important thing you ever need if you want to customize your Tech Decks. One end is a screw driver and the other end is a type of wrench. The screw driver end is useful for putting the trucks on and off of fingerboards. The wrench end can be used to change wheels and take apart the trucks or tighten both of them. They come in some different types you could say,like one is in the shape of an "X" or it can be a the simple shape of a yellow cilinderal shape with like said up there one end is a screw driver the other a wrench.