Mettler Silk-Finish Solid Cotton Thread, 500 yd/475m, Black Whether hidden or highlighted as decorative stitching, SILK-FINISH COTTON 40 works perfectly when used for machine or hand quilting Cotton 40 is mercerized for high breaking and shrinkage resistance as well as giving it that Mettler quality silk finish for smooth and soft machine or hand quilting Manufacturer recommends needle size 80-90 100% Cotton