4 Spools of each color ? 16 spools total - Black, white, grey and natural. Snap bottom, thread saver mini-king spools. 750 yd per spool, 100% 30 wt Two-Ply Spun Polyester Serger Thread. For light and heavy sewing activities. Excellent strength and elongation in the yarn. Great abrasion resistance with superb colorfastness. Runs smoothly and perfectly through any serger.