Bernette B44 2-3-4 Thread Funlock Overlocker Serger Machine Taiwan, LED, Built In Rolled Hem, Differential Feed, up to 7mm Wide Stitch Width, 1300SPM*

What is the differential feed for? The differential feed always ensures smooth seams with knitted fabrics and crimp-free seams with fine fabrics. By adjusting the setting between 0.6 and 2, however, deliberate crimping can also be created, e.g. for decorative ruffles.