Yosoo 40/60/80 Assorted Colors Art Twin Tip 1mm/6mm Mark Pens Art Sketch Graphic Marker Pen Set+Pencil Bag (General Design, 80-Black) Attribute: Alcohol-based ink dries acid-free. Applies to: art common use and Animation design drawing For alcohol oily mark pen, pen tightly after use to avoid ink evaporation. Correct pull cap method, first pull out a little, remove the pen cap into the air, if they feel tight can swing up and down at first and then pull the pen cap. Perfect for cartoon illustration, sketching and scribbling, fashion design