Compound-Differential Feed

Compound-Differential Feed utilizes a feeder below the plate that raises up through the plate,
compresses the fabric against the presser foot in conjunction with a feeder above the plate
which both pinch the fabric and both move one stitch to advance the fabric together.
The feeder below the plate is in two parts, front and rear and can either be set to stretch
or gather (shirr) the fabric as it feeds.