Posca Markers are acrylic paint pens packed with high-pigment, light-fast, long lasting ink. The ink is waterproof, fade resistant, non toxic, with vibrant colours. Posca's can be used on metal, wood, glass, plastic, plaster, canvas and more. They are used by artists, auto dealers, surfboard artists, auto body shop estimators, sign writers, art & craft people, etc. Please shake markers well before use. The internal ball-bearing should be moving freely back and forth. The nibs are activated by pushing down on the tips. Keep capped to avoid drying out.