Uni 0.5 Mm 2b Nano Dia Blended Hi-quality Mechanical Pencil Leads, 40 Leads X 10 Tubes, Totally 400 Leads of 0.5 Mm 2b 0.5 mm 2B uni mechanical pencil leads 40 leads X 10 tubes in original box smooth, dark, strength, tough leads They give a great balance between hardness and brittleness. They write smoothly and cleanly without constant breakage.