These socks are heavy duty. Coming out of the box you feel the weight and they are thick. However, when you put them on, they do not feel hot at all, just well climatised. The bamboo material is indeed great. Even after long sweaty walks the socks are still fresh, no smell! I have washed them often by now and they are still very much like they were new, no holes,stretched areas. I even wear them to play soccer. Recommended.