Lol, when i worked as a commercial diver i decided to use a pack of foot warmers inside my dry suit for a long winter dive. Believe it or not those things get super hot under pressure. 😅 Trust me putting one of those between two sets of socks then going for a dive will give you a very hot foot lol. Only did that once. Ha ha ha. But using them under normal confitions they fo help if you are outside in cold weather.