nctry_Ben wrote on Jan 31^st, 2011 at 1:42am:

What does KF have for sizes? I'm thinking the Medium and the Fine...?

The particular stainless steel knife that I use seems to get a quick good edge with the med grit. Most fillet knives are stainless steel - a very hard material. You could use a fine grit sharpener but it would take longer to get a good edge. With med. grit it only takes a couple swipes on each side of the blade to touch it up. Don't let it get too dull before sharpening. Also I don't think you could do too much harm with a coarse grit on stainless steel either. I have all three versions of the sharpener and have settled on the med. grit as the best for the particular fillet knife that I take on canoe trips.
BTW these ultra lightweight sharpeners look very disposable and at about 10 bucks a piece I thought I would need a new one every trip. Well, one summer,  3 10-day trips plus at least a hundred fish cleaned during the fall season in Wisconsin and the first of these sharpeners is still doing well. I am impressed.