Bernina L450 234 Overlock Serger, MTC Micro Thread Control, Roll Hem, Diff Feed, Tension Release w/Presser Foot Lift Lever, 3-9MM Wide, 1200SPM, 2LEDs

Have you ever been sewing with knits and completed your seam only to notice that edge is now longer than when you started? And perhaps it has a funny waviness that wasn’t there before . . . well, you are not alone. WHAT IS DIFFERENTIAL FEED?