M is for Magic Thread
A plied cotton thread/  black and white, designed for a specific end use in the manufacture of cloth, way back when I worked in the textile industry.
It is fine and really swell for stitching, unlike a lot of bakery string style thread available for crafting. I have several samples here that I developed. I wanted to offer it in my shop, but the manufacture on a small scale is way too impractical and nearly impossible to source. It is very special and I call it magic because black and white is my symbol for magic.  I do occasionally offer small amounts in the shop. You might mimic it by using a wrapped backstitch.