Unlike permanent markers and art markers, which can contain chemicals harmful to animals, Animal Marker use "legal pigments". These pigments are nontoxic and devoid of any hazardous materials. For use on the rodent's coat. Colour will not remain on the animal's skin. Nontoxic and devoid of any hazardous materials* A single marker can be used to mark 300-500 animals (depending upon animal size and/or applied area). Once applied, colours remain for 6-12 weeks.