The K-51 permanent ink marker is an ideal choice for coloring large areas with smooth, even strokes. The extra-broad valve-action nib is excellent for large drawing, lettering and calligraphy. It features translucent ink that can be overlapped to create new hues, and a double-edged tip that provides line variance and versatility. The ink is alcohol-based, does not contain harmful solvents and is xylene-free. Each marker contains 30ml of ink. They conform to ASTM D-4236. Handmade in the USA.