This is a worth while product for the homeowner who cuts on the weekend or a few times a year. I have a bench mounted sharpener that is now collecting cobwebs. This sharpener is well made and about 1/2 the price of the identical branded one.
About 5 minutes to sharpen a blade. This saves time over bench sharpeners. It knocks down the rakers as you file, another time saver. It does a better job sharpening than my bench mount.
The outer lip that holds it to the seat also makes it impossible to thread the nut onto the fitting. Tried to use these just to try them out and couldn't get below 900 microns. Such a waste.