It is called a Block
https://theblocksharpener.com
This one will sharpen regular blades, serrated on both sides and serrated on one side.
I have looked for something to sharpen my electric American Angler blades for years. They have got expensive enough that this is a deal and believe it or not it works.
Watch and follow directions, might as well order two and give one to a friend.
I promise this is the real deal