The groove in this foot allows up to three strands of side by side yarns or narrow ribbons and cords to be couched simultaneously. A latch at the front of the foot holds the yarns / cords or ribbon in place whilst sewing.
 
A black hinged 'gate' on the left side of the foot swings over the the cords. This holds them in place and prevents twisting and tangling whilst feeding under the fot.
 
Large cutout area under the foot allows the 'cords' to pass under without inhibiting the fabric feeding.
 
Select stitches that go from left to right with a width that covers the cords.
 
For Bernina models - Digital electronic machines up - Category codes B - F