PrimaLoft® - PrimaLoft has been in the advanced materials technology solution game since 1983. Originally developed for the U.S. Army, their high-quality microfiber thermal insulation systems mimic the warmth-providing properties of down, and have become synonymous with cold weather comfort. PrimaLoft fabric has millions of air pockets that actually trap and preserve body heat, and also contain fibers that are treated so that they don’t retain water.