Lots of things slow you down, ThermoPlume isn't one of them. PrimaLoft® Insulation ThermoPlume® is a lightweight, airy synthetic that acts like down and has some pretty impressive properties. It’s actually blown in to jackets so it’s easily compactable, making the “packs-right-into-itself” factor a breeze. Plus, it’s guaranteed to stay warm and fluffy even when wet. Best of all, you can toss it in the wash ... WITHOUT TENNIS BALLS! Smoosh. Wear. Wash. Repeat.