Start by choosing the body size: A Short body, if you like a small pocket size marker or a Long body if you would like some more capacity! Then next: choose from 3 different size Marker heads: The standard 15mm, The 30mm and the 50mm! If you like it simple: take the standard empty Transformer: An empty marker, short or long with the 30mm head. Also, if you are more the pre-filled type: select the size of the marker (short or long) and pick one of the 5 hard to buff colours! All markers are easily refilled through the back of the marker. All markers are to be filled with liquids: like ink or paint.