These pens have a waterproof, quick-drying pigment ink that will not feather or bleed through even the thinnest papers. The inks are smearproof once dry and fadeproof against sunlight or UV light. This package contains six 5.25 inch long pens - 2 black, one red, one blue, one green, one sepia - with .35mm tips. Archival quality. Conforms to ASTM D 4236. Imported.