In 1979, when Malden Mills first sold their lightweight, hydrophobic polyester fleece under the trademark Polarfleece, they did not realize that they would be coining a term, i.e., polar fleece, that would eventually come to describe a type of fabric rather than a brand.

Malden Mills' original fabric was revolutionary because it was both lightweight and warm. It picked up less than 1% of its weight in moisture, and even when completely wet, it maintained its loft and insulating properties. It made an ideal outerwear fabric because it actively wicked moisture away from the body.

Today the term polar fleece is applied to a class of high technology, high performance products that offer tremendous warmth relative to their weight, that are soft to the touch, and that are able to wick moisture away from the body so that they feel dry even when soaking wet. This class...