Box of 100 Groz-Beckert 175X7 Ball Point Industrial Button Sewer Machine Needles. Needle system* : 175X7 (FFG/SES Ball Point) These needles also cross to these different needle systems : 2091, 175X7, 29-L, 2091, SY4531, SY8728, TQX7 These are the same exact needles under different names and numbers. *A needle system is a group of needles made to fit specific sewing machines. All needles in a system are of the same length and shank size, but are of various diameters. Lower size numbers are narrower or thinner needles used for lighter materials. Higher size numbers indicate a needle of thicker diameter, used for heavier materials. Match your needle system to your machine, then the size of the needle to the product you are sewing. Ball Point (BP) needles are designed to alleviate making holes in knit or loosely woven materials. The cross fibers which constitute the knit or loosely woven materials are relatively far apart as compared to those in tightly woven material. When a needle with a standard "sharp" point encounters one of those fibers in penetrating the fabric, it cuts right through the fiber. This creates a hole in the fabric. The Ball Point needle pushes aside the fiber it encounters in penetration and thereby avoids making a damaging hole in the fabric.