J. Herbin Inks Fountain Pen Ink Cartridges Colour - Gris Nuage (Cloud Grey) uses all-natural dyes in its formulation; Snap-in cartridges are packed neatly and securely in small cylindrical metal tin box. Inks are pH neutral, non-toxic, lightfast and water based. Ink flows smoothly, fast drying and easy to clean out, making it ideal for beginners; Fits most fountain pens and rollerballs. Perfect for fountain pen users, calligraphers.