It is a slender strand of wire, shaped to precision that delivers thread to the machine to create a stitch. Sewing machine needles have become more sophisticated because of new sewing threads and novel fabrics available in the marketplace. Needles are found in various sizes, with different shapes and with more than one needle on a single crossbar.
Most needles use the two number measuring system.
The higher number relates to the metric system used in foreign counties. It defines the needle shaft diameter in fractions of a millimeter. The lower number relates to the system in the U.S and is used to indicate needle shaft diameter. The rounded tip slips between yarns rather than piercing them to eliminate damage in knit fabrics. Use this needle when working on coarse knits, mesh fabrics, interlock knits and other fabrics that tend to run if snagged.