Contains high quality water-based paint made with a high concentration of lightfast pigments that cover well;It is water-proof and abrasion-proof and can be used on almost any surface, indoors and out (though when using outdoors it should be varnished);The paint is safe to use, it is solvent-free, ACMI approved and each marker carries the AP mark of non-toxicity;Refills can be used to refill your Montana Acrylic Paint Markers or for airbrushing, mixed media, and brush applications.