The Skin Doodler Pens are made specifically for drawing directly on to the skin. The Skin Doodler Pens are made with a 1mm ball point and are 4.25" long and are 1.6mm thick. The 1mm ball point rolls onto the skin with little effort. These pens are great for free hand outlines. These pens are filled with sterilized ink from Japan and they are proven to be safe and healthy for the human skin. The pen tip is made by a swiss machine which provides an even ink flow to the pen.