Overlock thread is used for finishing, or overlocking, heavily frayed fabrics, as these would otherwise fray into the seam after several wears or washes, resulting in visible holes in the seams. It is thinner than regular sewing thread, yet very tear-resistant. Because overlock and cover stitches require much more thread than those sewn with a home sewing machine, overlock threads...

Overlock thread is used for finishing, or overlocking, heavily frayed fabrics, as these would otherwise fray into the seam after several wears or washes, resulting in visible holes in the seams. It is thinner than regular sewing thread, yet very tear-resistant.