Copic Original Dual Nib Markers contain non-toxic, alcohol based ink which dries acid-free making them ideal for design, fine art, illustration and more. Each marker contains 2 ends so you can instantly switch between a broad nib for thick strokes and a fine tip nib for precise, detailed work. The markers are double ended so you can go between broad strokes or a fine tip without reaching for your pencil case. They're great for use in design, fine art, architecture, illustration and more. The ink dries acid-free so it won't react with your paper. The marker has a square body so it's comfortable to grip and won't roll away when you put it down. Each marker is printed with its colour name and number so you'll always be able to find the right one. You can refill the ink or replace the nib as needed. This marker is known by the colour and code N4 Neutral Gray No.4. For best results, use a bleedproof paper or blending card.