I used these boots for the month of October in the Alaskan arctic, mainly on barrier islands and sea ice. Temperatures were 0-25 degrees (fahrenheit) and we often had 5-15 mph winds. I was outside, crouching and mostly not moving, for 1-2 hours at a time. My feet did occasionally become cool, but they never became cold to the point of discomfort. These boots possess thick insulation, and a layer of waffled material under the foot, which must help trap warm air.

One note - I wear about a size 9 shoe, and I ordered size 10 boots. When the boots arrived I almost sent them back because they felt so tight; however, after several days of use, the insulation packed out to a surprising degree and the boots now almost feel too large.

I purchased this boot for my "Alpina cross-terrain" backcountry cross country skis, with Rottefella NNN BC bindings. It has been a great setup, and it floats extremely well even in soft snow (when I am with friends who are wearing snowshoes, I seem to sink about 2-3 inches for every 10-12 inches they sink). The boot is very sturdy, and almost as comfortable as good hiking boots for walking. It is warm, but I'm glad I went with the slightly larger size for extra thick socks and toe-wiggle room.

Worked well in bighorn mts, wyoming. Positive: Very light, made solo infinitely better. No setup. Packs smaller than my sleeping bag. Kept me completely out of wind/snow/frost. Negative: I'm 6' even, wishing I got the extra-long, as putting clothes/raingear/camera in sack with me for the night made it pretty crowded. Some condensation on the interior floor after nights of 10-20 degrees fahrenheit, but easily wiped dry. Overall: definitely worth it.