Don't laugh. After the Rambo movies those things were the shite if you were 12 and didn't know any better. I had/have that EXACT knife that I bought from the local flea market for around $11. I remember using it to hack at japanese knot weed all summer long. The stone was some sort of super abrasive, I'd compare it to pumice. Never saw that commercial but just imagine what it was like for a kid to find something like that before the internet, when word traveled from person to person.