That would be a carbide tipped hole saw.I was wondering about a hole saw for metal, but didn't have a chance to look into it. Also wondered why there wasn't a bit made out of grinder material. Seems like that would cut like butter though it would wear out fast.
We use them to drill (handheld) through 3/8"-5/8" thick walls of ductile iron pipe dry. They work fine and last for many holes.
They do not work well on thin unsupported stock due to the pressure needed, and they definitely won't drill anything worth a damn but metal.
