Altrec.com:

Warm up to the notion of sleeping on snow and cold rocks with Exped's Downmat 7 air mattress. This down-filled mattress features high loft goose down with three times the insulating warmth of any mat with a similar weight, so it helps keep your backpacking and climbing sleeping bags working at their optimal thermal rating potential. Exped noted in recent studies that heat loss to the ground is often three times greater than heat loss to exposed air, which means that many climbers, snowshoe enthusiasts and winter backpackers are better off spending their money on a better mattress than warmer sleeping bags with lower temperature ratings. The Exped Downmat 7 air mattress can reduce heat loss by a staggering 65%, and because the mattress is insulated with down instead of foam, it packs into a diminutive 10 x 5 in. stuff sack. While the Exped Downmat 7 air mattress could compress further, light foam barriers built into the mattress prevent the down from sifting through the valves or migrating between the baffled chambers, eliminating cold spots. This Exped Downmat 7 includes a distinctive pump/packsack that allows quick and full inflation within minutes, so you never have to worry about the humidity in your breath dampening the down fill (the down fill has a special Nocar treatment to minimize condensation throughout many seasons of use). If you need a little more cushion and more thermal protection for outright frigid conditions, check out the Exped Downmat 9.