Fiber fineness is one of the factors determining the quality and performance of a wool product.
In recent years it has also become an important marketing device used by many mills, garment makers, and retailers.
[3] Each S-number correlates to a maximum fibre diameter measured in micrometers, as shown in the table below.
However, for fine wool, the memory of the older system survives in the S numbers which have a very rough correspondence to worsted count.
IWTO is the international body representing the interests of the world's wool textile trade and industry.
The Act was modified, for wool products manufactured on or after January 1, 2007, by the Wool Suit Fabric Labeling Fairness and International Standards Conforming Act which defined the use of the Super S and S designations in a manner conforming to the IWTO Code.