Long Arm Cylinder Bed Double Needle Compound Feed Sewing Machine | Long Arm Filter Bag Sewing Machine for sewing collapse ring in the milddle of filter bag Features: ES-4431 long arm sewing machine use synchronous feeding system to prevent the material slip. Upper and lower axis is driven by synchronous gear belt. Needle distance is adjustable by setting the knob. There is a safety device to protect the machine in case of overload. Energy saveing servo motor; Pneumatic presser foot lift; Automatic needle position (needle is always above the fabric after sewing)