System 16x231 is generally used in single needle lockstitch industrial sewing machines. It is also known as 16x257, 1738, 2270, DBx1, and DBx257; and in sizes 9 through 18 only as 16x95, 287WH, 1738A, and 1738AK. Please note that 16x231 refers to the system, or type of needle; size (diameter) is denoted by the suffix. For example, 16x231-9 is the smallest, or thinnest size we offer in this brand; 16x231-23 is the largest, or thickest size. The eye of the needle increases with the thickness to allow for sewing heavier threads. Needles listed here are standard sharp point only.