Solid Marker Glow-In-The-Dark is the first marker of its kind to incorporate safety-grade photo luminescent material for easy Glow-In-The-Dark applications * It can write on, stay on, and glow on smooth, rough, oily, wet or damp surfaces * Easy twist-up paint stick advance and secure cap keeps this paint marker ready to use * Alcohol based cleaners will remove ink from non-porous surfaces * Meets ASTM E2072-02 Luminance Standard