from the manufacturer:
A dazzling, versatile specialty thread that brings light and reflective qualities to stitching. Has a better stitch coverage and a smoother feel than most other metallic threads. Stitchers can work with 1 to 6 strands, either alone or in combination with floss or other needle craft threads. A polyester metallic and viscose blend that is washable, dry cleanable and resistant to tarnish.