This is a tool that is used to channel energy. In our tradition, it's aligned with the element of fire, and so is one of the symbols of fire on the altar. Traditionally, it's made of wood, and is at least 18 inches long, but not more than 36 inches.
In our tradition, it can be made of anything that feels "right." (I know of one person who uses a rosewood fountain pen!) This, once again, is up to the individual.