Pigma Micron pen 0.4 mm.
The Pigma Micron pen has an 'archival ink' that is pH neutral (archival-proof).
It is therefore often used on paper in the museum and archive world and in artistic contexts, but can otherwise be used on almost all surfaces.
The ink is permanent. It dries relatively quickly and will not disappear or rub off. The ink is waterproof and lightfast and does not penetrate the paper (most types of paper). The ink is produced from a combination of pigment and water.
It is available in sizes 0.2 - 0.25 - 0.3 - 0.35 - 0.45 and 0.5 mm. and in a case with all 6 sizes.
Pigma Micron pen
Pigma Micron data sheet