This device is equipped with a collar ring and is fed into the overlock sewing machine through a cylindrical upper and lower differential feeding. The collar sewing process for T-shirts and knitted sweaters is extremely easy for anyone to sew. The front feed type differential feed into the safety cylinder of the sewing machine has a protrusion behind the needle drop, making various cylinder operations very smooth. The most suitable inlay for the oil neck, collar, waist, etc. of knitted sweaters can have an outstanding effect on the neckband craftsmanship! Ensure high quality, uniformity, and perfect craftsmanship.