1. The left feeding roller ensure the fabric and tooth synchronous to convey smoothly. 2. Rectifying devices，control the body edge more sensitive and stable , ensure the overlapped stitch and seam allowance consistent. Extend the suitable range for the regular radian unit. 3. Fabric adaptability widely, different fabric color can be switched easily. 4. Infrared detection assist to locate the rear seam position accurately. 5. Automatic seam inspection，can detect the seam position and start sewing, even the rubber band is placed arbitrarily. 6. Automatic differential adjustment device to achieve uniform sewing effect。 7. Highly automation, adjust simply, operate easily.