Uni Posca paint markers create vivid color on practically any surface, including paper, photos, glass, wood, plastic, and metal. The opaque, water-based ink in Uni-Posca Markers dries to a matte finish on both porous and nonporous surfaces. These markers are great for posters, signs, sketching, lettering, graphs, and charts with odorless, fadeproof, and bleed proof.The paint ink can be scraped off from nonporous surfaces like glass but adheres permanently to porous surfaces like paper. It shows up well on both light and dark surfaces, and once dry, you can write over it with another Posca marker without smearing or showing through. The ink is water-based, non-toxic, lightfast, and waterproof.To start using the marker:Shake it with the cap on so that the ball inside rattles.Uncap the pen, place the tip on a piece of scratch paper, and press down so that the tip is pushed back into the pen's body.Press the tip down several times until the ink begins to flow.These pens have a fine tip, which produces a line between 0.9 mm and 1.3 mm wide, depending on writing pressure.Tip Size: 0.9 mm ~ 1.3 mmTip Type: BulletInk Color: GrayInk characteristics: Multi-Surface (like Glass, Metal, Plastic), Nontoxic, OpaqueInk Composition: Pigment-Based, Water-Based, WaterproofLength: 14.2 cm / 5.6 inches