Industrial Phano China Markers make beautiful, bold strokes on almost any porous or non-porous surface, like glass, plastic, film, paper, metal and rubber. Writing marks are water-resistant and colorfast but wipe away clean from porous surfaces. No need for a sharpener - each pencil comes wrapped in paper with a tear string for easy sharpening. Versatile markers can be used for textbooks, chemistry labs, marking food storage bags and even in construction environments