I was recently given a Knife Sharpener as a gift.... when I looked at it, I was not very hopeful that it would work, but as it turns out, it is the best and most effective sharpener I have ever seen or used. It is currently on my boat, so I cannot give you any specifics about it right now, but I will tell you what I can.
It is a system. There are 2 gray stones, 3 sided, that are about the size of a pencil. They fit into the base, at a fixed angle. You draw the knife down, STRAIGHT DOWN, along the CORNER EDGE of the stone to the right, then the left, then the right, then the left, until you have done so about 20 times. You then turn the stones, in their base, so that you are using the FLAT SIDE of the stone. Repeat about 20 more times. Each time, pull the KNIFE STRAIGHT DOWN. This ensures the proper angle.
After you are done with this part... you do the entire process again, with the WHITE STONES that are provided. First on the CORNER EDGE of the stone, and then on the FLAT EDGE of the stone.
I gotta tell you, this puts the best and sharpest edge on my knives. I love it. If you interested, let me know, and I will look at it when I am on my boat this weekend, and report back.