These black Staedtler Pigment Liners are truly versatile tools. Long metal tip & softer writing action makes them easy to use with rulers & templates for technical & architectural drawing. Lightfast, ultra quick-drying, smear-free & indelible. Since they’re waterproof, you can also use them with watercolours or other water-soluble media without bleeding. & if you leave the cap off, you can leave them for 18 hours before they dry out.