Commonly referred to as a grease or china marker will write on just about any surface, even under water. It will wipe off of any slick, non-porous surface with a dry cloth. Completely non-toxic. Highlights points of interest on a film. Wax markers resist smudging, but are not permanent. Not to be used in place of lead markers. Not a legally acceptable marking method.
Marking pens come 5 pens pre pack.
Others colors are also available: Red, and White