The Sakura Graphic 3 pen is a square-cut chisel tipped archival quality drawing pen. Featuring a 3mm tip and Pigma ink that is less susceptible to UV rays, chemical degradation, and pollution from contact with oils and other chemicals. Pigma ink has become the standard for what is defined as reliable, permanent, archival quality ink. Sakura Graphic pens are disposable technical drawing pens packed with archival pigmented ink. They are waterproof, fade-resistant, quick drying and bleed-proof on most papers. The durable nib and strong plastic casing makes this the go-to fine liner for illustrators and architects alike. - Sakura Black Pigma Graphic 3 Pen - 3.0mm square-cut chisel tip for a consistent line - Pigma Ink which is water-based and will not bleed through paper - Archival quality, indelible, lightfast, and dries to a neutral PH