The Gasenfude Brush Pen delivers all the flexibility of using an ink brush but in pen-form. This flexible brush nib creates expressive line variations and is made of water-based pigment (which means that it's Copic-proof). That means that when the ink dries on your paper, it won't bleed into any of your Copic markers (and you can color on top of the Gasenfude ink with your Copic markers and no smearing will happen). · Dimensions: 8.1 x 1.9 x 0.5 inches · Item Weight: 0.4 ounces · Water based pigment ink (becoming waterproof when dry) · Acid-free · For illustrations, Sketches, card making, and writing use