A modern mechanical pencil, just click to advance the 1.3mm lead-twice the thickness of standard fine leads. Clearly seen lines in white, blue or pink. So much sharper and cleaner than chalks. No gritty or powdery residue. Erase easily with water or a polymer eraser. The rubberised barrel is comfortable to hold and enables a clear view of what is to be marked. This disposable pencil gives a substantial length of line while saving the trouble of stopping to sharpen.