These socks are great! I saw that other people leaving reviews say they don’t work. Before using, read the instructions which are not confusing! AND REGISTER THE PRODUCT!! I live in the Midwest and hunt a lot. These batteries last all day! I set the timer for 15 minutes at a low temp that you can put at any temperature. An hour later, I do the same thing. You don’t need to have these on for a long period of time or your feet will start to sweat. They are controlled by an app on your phone that allows you to pick time and temp. And the app is very easy to install and use. NO MORE COLD FEET!