that's a ball hone. and what he was talking about. Flexhone makes them.
be sure you get the one with the Aluminum oxide balls on it NOT the silicone carbide. 280 grit.
I think the one I have is 89mm. I can't remember. but if you read the spec's of the hone they will tell you what sizes to get.
I get mine from MSCdirect.com. just because I can drive 30 miles to pick it up in an hour
Here's a tip when you do them.
put the 2 cylinders together as one long cylinder. I use 2 clamps to tighten them together. The cylinders will be offset. if you have a piston that goes with the cylinders set that in as a "jig" and then clamp them so you can ensure that it's a perfect fit. This way the balls don't scar the surface of the headgasket seating surface.
when you are done. wash them with dish soap and water. Oil them with a clean paper towel or rag until all the grit comes out of the cylinder, then wipe them with clean oil and you are set.
it doesn't take much to do it. just a few runs at low speed. also use a surfectant like Kero or Diesel fluid for the hone. a gallon or 2 in a bucket works just fine.