This high quality metallic thread from YLI is smooth-sewing, strong and brilliant. Nylon core gives strength, rice paper is used for better bonding and stability, and it has a silver alloy film undercoating. Designed to stitch 1000 stitches per minute! Used in high speed embroidery machines, sergers and home sewing machines for decorative sewing, couching and free motion embroidery. If you have tried other metallic threads and have given up because of constant stripping and breaking, give this strong and reliable thread a try! (And use your Metallica needles - changing often!) 500 yard mini king spools, color #040, YLI Color Persian Blue.