The needle of system 135X39 has a small ball point for working knit fabrics, without damaging the stitches. It is used in industrial overlock, coverstitch and safety-stitch machines for elastic knit fabrics. Suitable machine classes are found, among others, at Necchi (classes 815, 835, 881, 885), Rimoldi (classes 815 - 03, 815 - 102, 815 - 103, 835 - 100) and Singer (classes 270, 270 - X 11, 270 - X 13, 270 - X 18 TO 29).
Thinner needle sizes are used, among others, for fine, light jersey and tricot fabrics, and the thicker versions for heavy, dense knit fabrics and technical knits. As sewing thread, a matching thickness is usually recommended depending on the needle size chosen, e.g. from Amann Serafil or Rasant; for very stretchy seams, a texturised thread also works well. The ball point glides between the loops instead of piercing them, keeping the seam clean and undamaged.