Write on any smooth surface; ideal for plasticware, glassware, photos, slides, and more. Waterproof, nonfading ink dries instantly to prevent smearing and bleeding. Extra-fine, plastic writing tip stays sharp and precise. Pen’s unique, long leg lays flat against rulers and flexible curves for accurate alignment. Pens are perfectly balanced to comfortably fit in your hand. Instant writing, long storage time, and dry-out prevention are ensured by an airtight ring seal in the cap. Pen responds the moment it is touched to paper.