Glad I helped ... I didn't know all about the different feet when I got my 6600, and added them later. When I mentioned that I was not aware of them, and was disappointed they had not told me, they sold them to me at their cost!
When I switched machines, I studied all the feet and made my list of what I might possibly want ... and that was negotiated as part of the package in purchasing the machine.
Good Luck ... and enjoy!