ZIG Brushables are a flexible felt tip, two-toned pen, great for brush techniques and for creating two-toned blending effects. Pens are acid-free, photo safe, and have two tones per marker. Waterproof / Archival Quality / Ideal for Scrapbooking and other crafts / Twin brush tips: a popular color of MEMORY SYSTEM on one end and the other end slightly tinted with the same color