Disposable Technical Pen Marker uses a special formulation of highly reliable, permanent archival pigment based ink that is more chemically stable than dye based inks. Waterproof, chemical proof, fade resistant ink won't smear, feather or bleed-through on most papers. Pen markers provide skip-free writing and crisp colors that leave consistent lettering and lines every time. Technical professionals, artists and crafters choose from a range of six nib sizes for precise line widths that correspond with the task at hand. Nib sizes 005 = 0.20mm, 01 = 0.25mm, 02 = 0.30mm, 05 = 0.45mm, 08 = 0.50mm. Pigment based ink meets ASTM and ACMI nontoxicity standards.