Used for topstitching quilts with thick and thin padding.  The clear sole ensures unobtructive view of the entire sewing area.
 
Especially suited for free motion contour quilting, thread painting and stipple quilting.
 
Designed for Bernina machines with a maximum stitch width of 9 mm.
 
The sensor (the letter 'C', in the foot number) is for coded and refers to the sensor that apecifies the stitch width to the sewing machine.