strength & Deep & smooth -Uni-ball Extra Fine Diamond Infused Pencil Leads, 0.7 Mm-2b-[nano Dia]40 Leads X 3 Pack/total 120 Leads Uni develops the lead of the top quality Intensity of the lead was sharply strengthened by blending the particles of a diamond. Since particles have aligned by high density, it can write distinctly still more deeply And it can draw more smoothly.