Flat seam is a method that using sewing thread to form the thead track on the surface of material.This method can make one or more layers to stitch together. Fabrics are usually divided into two types, one is the thin material that is usually used in knitwear, shirts and anoher one is the thick material that is used in all kinds of sportswear, jeans, coats, shoes and hats, leather Aberdeen, bags, etc.