the livestock marking crayons made of real paint, which is used for vaccination, heat detection, identification and sorting of the livestock. the livestock marking crayons can mark on wet or dry livestock, and they are non-toxic and safe for all livestock. the livestock marking crayons are available in various color, such as red, fluorescent yellow, pink, green, blue,etc. the marks on the livestock’s skin can be effective for 7~10 days depending on weather condition. so this livestock marking crayons are ideal choice for marking cattle, pig, hog and almost all livestock.