Madeira Aerolock Premium Serger thread is a top quality, core-spun thread guaranteed to last through frequent washes or strain. Like all Madeira thread, each cone undergoes extensive quality testing to ensure flawless stitches every time. Available in 48 colors. Each spool contains 2000 yards of 100% core-spun polyester, no. 125. Works on all sewing, overlock and coverlock machines.