9 piece S/M/L Refillable Water Brush Ink Pen For Water Color or Calligraphy - sold per 9 piece set How to use: Unscrew the pen, fill with water or ink or paint (media). Paint may need to be thinned and may be harder to rinse out. Squeeze pen to fill fibers with media. Wipe on paper to adjust media load. Squeeze pressure with allow correct media to flow out as you desire. Refill as needed. How to change color: Rinse pen making sure to remove all media from brush fibers. When not in use, clean pen and brush well, allow to air dry, replace lid and store as needed. Brush material: fiber strands Pen material: plastic Great for watercolor coloring books, no spilled water ;o) well not as bad