The Tombow Mono 100 is sometimes said to be the world's best pencil. Easy to write with even with a soft hand, but with a lead that can also handle quite a bit of pressure. But the name - 100? What? Well, the Mono 100 contains a lead core with 10 billion particles (or - to make the name make more sense - a hundred hundred million) per cubic millimeter. Unbelievable? Yes.