AFFORDABLE REPLACEMENT : When you run out of the black pen in your dual tip brush pen set, it is an affordable and convenient way to buy this product as a replacement instead of buying a new set PREMIUM INK : This dual brush pen uses water-based ink, which is odorless, non-toxic and quick-drying. You can safely use it without worrying about messing hands or books DUAL TIP DESIGN : Each black marker has a fine tip and a brush tip. The fine tip works well for detailing and lettering and the brush tip is suitable for colouring. The combination of the two tips will make your drawing process more efficient and pleasant MULTIFUNCTION MARKER : These brush pens are versatile, adults and kids can use them for sketching, hand lettering, journaling, drawing, colouring and so on NOTE : After using the black marker, please close the cap in time to prevent the surface of the pen tip from drying out. And when you use the fine tip of the pen, don't use too much force to avoid tearing the paper