Mono Work: Mechanical pen with 0.05 inch (1.3 mm) lead The thick core is hard to break, so you can write dark and clear lines even when writing on a rough, so it is recommended not only for examinations, but also for notes and ideas, or as a first mechanical pencil Core: Adopts a newly formulated sharpening lead HB that can be erased cleanly with an eraser Eraser: The eraser on the back is a mono eraser, so it is excellent for erasing performance and point erasing. (Please use the manufacturer's part number ER-MG to refill erasers.) Mechanical Pencil, Simple design with no alphabet letters that can be used without concern even at the test site. The knock button is short-sized to prevent it from touching the back of your hand while writing