These markers are most often used outdoors, as they will not come off in the rain. Use them on car windows, on the painted part of a car, plastic, glass, aluminum, steel and stone; any surface that is not porous will accept the marker. They work well on chalkboards and look like chalk when dry.
Even though they make a strong bold mark, they are semi-permanent and can be removed with Windex. The marks made are resistant to UV light, so they will not fade.