Mulching blades a problem.
The housing may work on flatter blades but it binds on the curves in my mulching blade (from a Black and Decker electric mower). However, the stone worked fine freehand.

Great tool for the sharpening impaired
If you have a Dremel tool and any kind of metal tools with an edge then you need this. I was skeptical, but found it works really well. It takes a little while to get used to so I recommend to learn on the less important tools like a shovel you rarely use or don't care if you knick it.

The grinding stone can bur into you edge if you aren't careful. And it's kind of hard to turn around the angles of a blade. But this sucker will sharpen every tool you have from the lawnmower blade to the axe to the sling blade (some people call it a keiser blade).

Sharpener
This tool loks great but it does not grind or sharpen as I thought it would.

Good Value
I'm sorry to see the other poor reviews. I have had this for years, and it's worked great every time. I have a push mower (Toro Super Recycler), single blade. The blade fits snugly into the plastic guide, and it sharpens quite well. No complaints. It saves me a lot of time, being able to sharpen myself, any time of season, as opposed to manually sharpening with a file, or taking somewhere to have it done.

Mower blades won't fit into the attachment
I don't know about blades of single-blade push mowers, but the blades on my Deere L108 riding mower absolutely won't fit into this attachment. They are way too thick - you'd have to snap off the bottom portion of the attachment to even get the grinding wheel to be able to reach the blade.

So don't consider this for riding mower blades, at least the ones on a Deere.