Refill diameter has to match the barrel, and the figure is printed on the pencil as well as the tube. A lead sized for one barrel jams or rattles in another, and a drawer of mixed refills becomes useless. Once the size is right, grade follows the work: harder leads for technical lines, softer ones for shading, though very soft leads snap in fine diameters. See mechanical pencil leads, mechanical pencils and erasers.

Colour pencil leads and mechanical pencils arranged on a bright drafting desk with project notes, technical sketches, ruler and eraser.

Pencil Leads for Mechanical Pencils

Shop pencil leads for mechanical pencils, drafting, sketching, study, office writing and technical drawing.