This is Sailor's Special Black Nano-ink. In this ink, the latest Nano technology is used. Let me tell you about this Nano technology. A normal ink is water like fluid which easily flows through the pens nib. But the normal ink can get erased if water is spilled over it or due to time and temperature, the ink starts fading. The latest Nano technology which sailor has adopted in its ink is that it never gets erased irrespective of temperature, time or water. It is a complete waterproof ink. The flow of this ink is very smooth and in a pyramidal way. The Pure Black colour of this ink is also deep and shiny.