Our Staytech Camprest mattresses provided excellent comfort and warmth in the field. They were the most wonderful piece of equipment we carried. While we encountered temperatures near -40 celcius at night, our mattresses gave us the clearance from the cold snow necessary in order for our sleeping bags to perform to their peak. When we encountered the extreme sub-zero temperatures, moisture buildup in the valve would freeze having an adverse effect on the "self inflating" feature of the mattress, but once inflated, we were in heaven!. On a future winter trip, we might exchange the air mattress system with a closed cell mattress. A punctured air mattress in the winter is not only frustrating but dangerous. Due to a small error we did puncture one of our mattresses. In cold temperatures repairing anything requiring dexterity is a nightmare. A closed cell mattress might not provide as much comfort, but would certainly not come with the added worry of puncture.