if you want to add whiteboard water or ink to the refillable markers, please the tip lightly, otherwise the ink be ejected from the pen tube without backflow due to the valve; When you want to add acrylic ink, paint ink and powder type ink, these powder particles need to reach nanometer standard the package contains 16 pieces of empty paint pens in 3 types, including 6 pieces of round head paint pens in . 3 mm/ 0.12 inch, 6 pieces of tilted head paint pens in . 6 mm/ 0.24 inch, and 4 pieces of flat head paint pens in . 8 mm/ 0.31 inch, together with 3 ml plastic dropper, sufficient quantity and various sizes the refillable paint pens are easy to operate and use, the white tube is convenient to know the dosage, easy to fill the color, just remove the nib area of the pen, put the steel bead into the pen tube, fill with paint or ink, then screw the nib back, you can writing; Be careful not to pull out the refill, it may affect the use the fillable ink pen is suitable for filling different paints or inks, you can fill empty tubes with different colors you like, including acrylic, oil, watercolor, ink and more, suitable for home, school, painting class and other, practical tool for students and painters the empty paint marker is mainly made of PP tube and polyester tip, with steel bead inside, to provide you with smooth writing, let you use it with confidence, the steel bead avoids the solidification of watercolor or paint, please pay attention to put the steel bead into the pen, for a better user experience; Tips Features: Easy to refill and hold: The empty acrylic marker comes with dropper, easy to refill, and the size of the acrylic marker is compact and portable, easy to hold in hand, convenient and practical. Please note that the quantity of the dropper is random. Nice gift supplies: You can send the empty paint tubes to your friends, classmates, colleagues, children and painting lovers