Coats S950 Dual Duty Xtra Performance Heavy Thread. Heavy weight for hand and machine sewing. Heavier, stronger thread for bold topstitching, cording and buttonholes. Use with interior and exterior upholstery fabrics. Has a polyester wrapped core, consistent tension and excellent stitch formation. Smooth, color fast and weather resistant. It is a 15 wt, 125yards per spool. Machine needle size: 1618, Hand needle size: 1, 2, 3, 4, or 5.