I suffer from cold extremities (hands and feet) and my feet are cold in these after about an hour even on the warmest setting.
For the money I feel they need to be better engineered.
I have Raynards so during the day I have been using rechargeable heated insoles,recently I got the thermic socks and I have them on all day and they help keep my feet warm, I have bought some extra socks from Amazon UK at £50 a pair so I can use the battery while the older ones are getting washed
Worth the investment
I have always suffered with cold feet on the slopes and was considering fitting boot heaters when I saw these socks. Wasn't sure about relative merits, but they seemed more flexible as they can be used with different boots and footwear. The store didn't know much about the product but web chat was helpful in advising on the pros and cons. Have just used them for a week's skiing and never had cold feet even just on the lowest setting. They might seem expensive but they work and well worth the price for warm feet in my opinion!! Will see how they last when washed, but for now very happy.