Uni-Ball 40108 207 Premier Retractable Gel Rollerball Pen, Medium Point, Black Ink, 1 Count Valve-action marker writes on virtually any surface: glass, metal, wood, rubber, stone, plastic, paper, vinyl, leather, canvas and more. Quick drying ink marks opaque and glossy on light and dark surfaces. The archival-quality, acid-free, oil-paint ink is fade-, water, and abrasion-resistant, ideal for projects that need to last. Ink is permanent and certified AP-non-toxic.