Strength & Deep & Smooth -Uni-ball Extra Fine Diamond Infused Pencil Leads, 0.9mm-2B-[Nano Dia]36Leads x 3 Pack/Total 108 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.