I got the Norton Flattening stone a few weeks ago for my waterstones. So far I've used it about 5 times and here's some feedback for all of you. The NFS is longer but not wider that the 3" waterstones. The stone is placed on it and slid back and forth to lap it. It does a quick and effective job. Norton stones get perfectly flat in a minimum of time. It leaves a slightly "rough" feel on the higher grit stones vs lapping with 600 grit sandpaper. The first time I used it on the 4K/8K, I finished it with 600 grit to smooth it, but I find that the 4K does cut faster when left rough so last night I left it that way after lapping. The edge of the razor that I'm working on looks fine under the microscope after the 4K. I might do an experiment where I leave the 8K a little rough and see how that affects the edge. So, the NFS has worked out great for me. I prefer it over the sandpaper, though I realize that many people out there prefer the sandpaper. I do think this stone is a great value for people who lap their stones a lot, cost is only around 20$.

One thing I've learned is that no matter which method you use, sandpaper or NFS, you will have to lap a norton stone. They need to be lapped when new, and after they get used for a while. When I lap a stone, the pencil marks that I use on it always wear off unevenly, indicating that the stone was not flat and needed lapping.

------Michael