Pack of 6 Empty Aluminum Body Fillable Blank Paint Touch-Up Pen Markers with Nibs. Each blank paint pen holds up to 0.58 Ounce (17 ml) of your own paint media material. Each pen has a premium 4.5 mm (0.18 in.) diameter fine tip nib that produces a line width of 2.5 - 3.00 mm (0.10 - 0.12 in.).U.S. Art Supply's premium blank paint pen markers can be filled and used with most types of paint coatings and ink materials. They work excellent with Art Acrylics, Oil and Water-Based Paints, Watercolors, Stains, Inks, Dyes, Automotive Coatings and Clear-Coats. Simply fill the empty paint blank tube body with your choice of custom paint colors. Leave the paint shaker ball inside the body before filling. Snap on the cap with nib, then give the pen a little shake and you're ready to go!To activate the paint flowing through the nib, simply press down on the nib a few times to get paint flowing. These premium paint pens have a unique capillary pump action to keep paint flowing, yet allow you to keep full control of paint flow.Artists love using our U.S. Art Supply premium paint pens for all their specialty arts and crafts, drawing, illustrations and auto paint touch-ups. They are a truly unique painting tool. Once you're done just press the cap on tight to seal it for the next use.