Funny, last week I was doing some buttonhole stitching on my older Bernina and decided to try this open toe which seemed to work the best. I didn't know what the foot was called until I did a search. This is what my #20 foot looks like:
http://www.thecolorfulworldofsewing....r-Bernina.html
It is easy to see if you are sewing a satin stitch on the edges of an applique