Mountain Hardwear Phantom -40 GTX Windstopper 850 Down Sleeping Bag - The Mountain Hardwear Phantom -40 GTX Windstopper 850 Down Sleeping Bag, constructed with GORE-TEX WindStopper fabric. The Phantom is breathable, highly water-resistant, windproof, and ideal for severe conditions. Insulated with goose down for optimal warmth-to-weight ratio and compressibility.