When it came to providing a durable, reliable, economical synthetic insulation, The North Face created its own as we were unable to find an existing option – Heatshield Optimal Technology™ (H.O.T.™ SL).
Built with 100 percent polyester hollow-core fibers, H.O.T™ SL provides powerful thermal efficiency. Because the fibers are of variable thickness, they compress easily, without breaking down, resulting in a bag that’s convenient to pack, yet doesn’t lose its softness, warmth, or high-loft.
