This knife reminds me a little of the dolly baby bottles with the milk that disappears. It is a plastic knife that looks plastic. THe blade is set inside a large clear shell. Between the blade and shell, purplish-red "blood" floats around when you move the knife. Probably fun for very small boy, but it looks rather cheap to me.

In short, great Halloween toy for little kids, but not a knife that an adult would want to use in a Halloween activity where realism is expected.