The Big Agnes Third Degree Foam Mat is engineered for extreme alpine conditions but is also a great ultralight options for all back country adventures.
Big Agnes says:
Closed cell foam provides a firm, insulated barrier between you and the ground. Plus, a comfortable backcountry seat on uneven ground and protection from snow or wet grass.
Suited to temperatures below -9C.
The Big Agnes Third Degree Foam Sleeping Mat is one of our lightest closed cell foam mats and offers more warmth than the traditional 'flat' design. This is because the mat is designed with die cut sections on the top layer to trap warm air and has a tire tread pattern on the bottom layer to create more cushion. These two foam layers combine for more warmth and comfort.
The disadvantage of this type of mat is its size - they are big and bulky but they can be attached to the outside of your pack. The advantages of a foam mat other than the weight of course, is that you can't get a leak in it so it won't fail. You can also cut it to the size and shape you need, thus avoiding carrying extra weight.
The Third Degree Foam Mat is ideal for those looking for extra insulation under your air mat on snowy night or an ultralight stand alone option for the back country.