I was wearing them to my trip to Everest base camp and Japan in winter. It worked very well. I’m happy with the purchase. Especially, walking 10-25kms a day was a blessing wearing this boots. Never got any problems with them, it was comfortable all the way, any condition. Warm enough for cold, not too hot when you get moving. The only thing is for extra cold (as well as high altitude) you might get 1 size bigger. At first I got my size and it was too small for 2 socks, i exchanged for a bigger one and it was perfect fit. Also very stylish. I felt pretty cool wearing this on the mountain. Although, I felt a little cold in -25C when summitted one of the mountain, but I’m skinny and my feet get cold very easy, so I guess it’s all good