On Mon, 22 Dec 2014 20:13:56 -0600
-MIKE- wrote:

Next time you're at a HF, I encourage you to pick up a set of these
bits because there are many, many other uses for them. They make
nice, clean cuts in metal and the HF ones are sharper than I thought
they would be.

For some reason I've got one of these bits, no idea where or why.
I don't think it was from HF so seems they're sold by others too.