Originally Posted by
Onebyone
I have this one and it is not for sharpening a dull blade but to keep a sharp blade sharp. It works great. I run my blade in it a every so often when cutting. The secret to keeping a sharp blade is to sharpen a sharp blade. Like cleaning a clean house, it never gets dirty.
http://www.sewforless.com/item/Grace...FVE8gQodCKQFdw
Mine actually looks like a ruler and not the one pictured. The one pictured actually looks like a great idea.