I tried a $200 pair from Cabelas a few years ago. In below zero temps you had to run them on high to keep your hands warm. They did a really good job for about an hour and half, then the batteries died. Not very much insulation in them so once the battery dies and the heat quits your hands get very cold quickly. The batteries will last longer on low or medium setting but didn't put out enough heat. I've since went back to just using handwarmer heatpacks in my gloves. Fingers get a little cold but you actual hand stays warm.