The Pitt Artist Pen Brush Set includes 6 vibrant colors, each filled with pigmented India ink that is lightfast, acid-free, and pH neutral. The waterproof, odorless ink becomes permanent on porous surfaces once dry. Ideal for detailed work and layering color, the flexible brush tip maintains its shape for precise control and smooth application. Perfect for sketchbooks, these pens won’t bleed through paper and work beautifully on various paper types and canvas.