I have the Bernina 830 and both 1/4" feet. The one with the guide is not an accurate 1/4". It's bigger!!! The one without the guide is a little bigger also. So I bought a scant 1/4" measuring tool and use my 34D clear wide foot and move my needle over to an accurate scant 1/4". Now I'm actually sewing a proper scant 1/4". So, I wasted my money on those feet. And my stitches look perfect!