The Klymit Ulaar Jacket doesn't puff you out like a down jacket, and it doesn't make you pile on sweaters like a shell. Instead, it serves as both shell and insulated jacket using an innovative insulator: argon gas. You can pump the jacket full of gas (insulation) when you're cold and let some of the gas out when you're warm.
Klymit calls the technology NobleTek, and it's been using it in a line of vests since 2009. The Ulaar jacket is the first shell with NobleTek.
Klymit says that noble gases like argon are a natural choice for insulation because they have low thermal conductivity. On a graph on its website, the company shows that 4.5 mm of argon insulates comparably to 14 mm of solid insulation.You stay warm with less bulk, and because the warmth is from gas, you don't get the added weight of heavy solid insulation.
Another NobleTek advantage is its flexibility. With Klymit's pump and argon cartridges, you can add insulation in the field when things get cold. Say you wake up to a beautiful spring morning, take off on a long day hike and, midway through, things get stormy and cool. Ordinarily you'd be left to suffer, assuming you didn't bring any extra clothing with you. But if you're wearing a Klymit garment, you can pump it full of insulation and up your weather protection for the altered conditions. Similarly, if you're hiking on a winter day, and the high-alpine sun starts pounding down, you can lower the amount of insulation to cool down without ripping off layers or lashing a sweater to your hydration pack.
Source: gizmag.comAdded: 11 June 2012