Review (1/5): Garbage product -- does not work at all
Really, do no waste your time. I bought these for my son's "crazy hair day" at school and they didn't work at all. The comb teeth prevent wetted hair from touching the crayons, so you really have to rub hard to get anything to come off. It got to be painful, so we took the crayon out of the comb and tried just rubbing it on his hair and that worked somewhat, but we still had to press very hard to get even a smudge of color.
If you want a temporary color, I recommend Colorista spray coloring. That's what I got this morning before school and it took 5 seconds to put in and was perfect.
This is a terrible product and the idea that you can achieve the effect depicted in the photos is utterly laughable. Whoever's manufacturing this should be ashamed of themselves.