Zebra Clickart pens are water based click top pens featuring "Moist Keep Ink" which contains a component that absorbs moisture in the air. With this invention, the pen repeats to absorb and evaporate moisture depending on the humidity, adjusting itself to its best balance. This enables the pen to write for a long time without drying up. Clickart works well with layering colors. Even if a light color is layered on top of a dark color, the dark color will not bleed. Please always store the pen tip inside. These pens are an answer to the many complaints regarding conventional pen caps; the ink get on their hands when closing the cap, and of course loosing the cap.