The needle of system 2091 KK has a large round point for sewing on buttons. The KK version has a short shank. It is specifically designed for industrial button-sewing machines. Suitable machine classes are found, among others, at Csepel (classes CS 600- 3AB, CS 600- 3B, CS 600- 31 to 31 D, CS 600-A), Adamson (classes BSO, BSO - 135-SP, BSO - 142 TO BSO 143, BSO - 150) and Chandler (classes 658, 758).
Thinner needle sizes are used, among others, for smaller buttons on light to medium-weight fabrics, and the thicker versions for large, multi-hole buttons on heavy coat and jacket fabrics. As sewing thread, a strong polyester thread, e.g. from the Amann Serafil range, is usually recommended, in a thickness matching the needle size chosen. The large, sturdy point reliably pierces both the fabric and the button's holes.