Exped DownMat UL 7:
When camping, the ground on which you will be sleeping is the biggest point of contact for your body, (unless in a hammock!). The ground then acts somewhat like a heatsink for a great deal of the heat given off by your body whilst you sleep, channeling it out of you by way of conduction. As such, if needing a sleep system capable of keeping you alive, warm and comfortable, a good insulating mat is of as much importance as a good sleeping bag. Down mats, or synthetic alternatives use the body heat that seeps down through the mat to warm air trapped in the down/synthetic filaments, thus providing you with a semi-passive, self-sustained bed of warm air to sleep on.
In this context, the Exped DownMat Ul 7 M is an excellent invention. It contains 700 fill power goose down filled baffles, (170g of down), that utilise your own body heat to warm air trapped within the down filaments, producing an R-value, (a little advice and information from REI), of 5.9, so it is well able to insulate you from the ground. Does it work? Emphatically, yes! At no point have I ever been anything less than toasty, even at temperatures of around -10C, (it’s rated down to -24C!). The down baffles are oriented length-ways, which means that you don’t roll off easily during the night!