Use these SINGER heavy duty sewing machine needles when stitching heavy fabrics such as denim or leather. Assorted needle sizes allow you to choose the needle that best suits your fabric. The blue needles have a sharp point and slender eye for sewing jeans and other denim fabric. The brown needle, used with leather and vinyl, has a triangular point designed to make a clean hole in non-woven materials. Color-coded sizes of needles include: size 90/14 for use on leather, size 100/16 for use on denim, and size 110/18 for heavyweight woven fabrics. Needles come in a carrying case with sizes marked over needle slots, and can be used on SINGER, Brother, Kenmore and other quality sewing machines.