rOtring Rapidograph Ink Capillary Cartridges, Black (S0194640) This is an easy-flowing, high opacity ink with excellent adhesion, suitable for tracing paper, vellum, drawing paper and lineboard. Ink is smudge-proof when dry. Won't erase with rOtring B20 and B30 erasers. It's lightfast and suitable for all forms of reproduction. Ink has high color purity. Colored inks can be mixed with one another. Limited warranty: guaranteed for 2 years from original purchase date against defects in materials or workmanship.