I purchased this attachment a couple months ago, and it has proven to be a real surprise.  Since it is an inexpensive tool, with the more inexpensive chisels and bits included, I didn't expect it to be a precision tool, but  it really does well.  I have now used it to make mortises in red oak, white  pine, and southern yellow pine, and am glad that I didn't spend more money  than I did.  The other reviewers are absolutely correct that set-up is time  consuming, but for a hobbyist woodworker like me, it does the job  efficiently, cheaply, and well.  I would definitely purchase this item  again.