What is the name of The North Face's synthetic insulation technology?

The North Face’s synthetic insulation technology is called ThermoBall.

ThermoBall was developed as a synthetic alternative to down. Its small, rounded clusters of synthetic fibers imitate the way down clusters trap warm air, creating insulation that is lightweight, compressible, and useful in a range of outdoor garments.

One major reason to choose synthetic insulation is performance in damp conditions. Traditional down can lose loft when wet because its fine fibers clump together. ThermoBall’s synthetic fibers are designed to retain more of their insulating structure when damp, making the technology practical for changeable weather and active use.

ThermoBall is not the same as Thinsulate or PrimaLoft. Those are separate insulation brands or technologies, although PrimaLoft has been involved in the development of ThermoBall. “Down” is a natural insulation material rather than a synthetic technology. Later ThermoBall Eco versions used recycled polyester, extending the technology’s design toward recycled-content products.