I received the insoles in December and was super excited to try them out on some cold hunts. The first time I took them out it was 34 degrees. I wore a pair or thermal socks and used the insoles and my feet stayed plenty warm. The next two occasions I used them was in 15 degree or lower temps. I was wearing 400-gram boots and somewhat thin socks as recommended in the instructions. My feet froze. I don't believe these are made for temperatures much below freezing unless you have heavy boots.  The insoles were built well and held up...