The 0.15-inch-thick windbreaker is as warm as a goosedownjacket 1.6 inches thick, says Champion parent Hanesbrands, which is considering a jacket for the retail market.
In January the two companies unveiled an aerogel fabric called Zeroloft, so named because it can trap a person's warmth without being puffed up to produce loft (as a goosedownjacket must be).