When you want to make the most of your serging time, with professional results, the MyLock 634D is unmatched. It has 2 needles and 2, 3 or 4 thread overlock stitching. Threading is a breeze due to color-coded thread guides and an easy lower looper threading system. The MyLock 634D also lets you quickly switch to rolled hemming without changing the needle plate. Key Features: 2, 3, or 4 thread serger Color coded thread guides Changeable thread guide Easily retractable upper knife Adjustable stitch length 1mm to 5mm Maximum speed 1,300 spm Lay-in thread tension dial Tension release device Quick change rolled hem Adjustable foot pressure Differential feed ratio 0.5 to 2.25 Waste chip box Threading chart Easily accessible lower looper guides Lower looper pretension setting slider Snap on presser feet Adjustable cutting width 3.1mm to 7.3mm