This type of foam pad is the lightest and warmest type of sleeping
pad per ounce. They are also completely waterproof even if damaged.
If you want to travel ultralight with the lightest possible load,
this is the pad to carry. They are also the cheapest backpacking
pad you can purchase. On the down side they are bulky and provide
only minimal cushioning making them the least comfortable.
The cheapest closed cell foam pads are simple rectangles, easily
cut down to size. A thickness of 3/8" and torso length provides
enough warmth for summer/three
season trips. For colder weather or if you sleep colder, a thicker
pad is recommended. For winter camping use a full length pad, and
you may want to double up.