3 HEAT SETTINGS TO KEEP YOUR FEET WARM: The heated socks come with three temperature settings that you can choose from according to your preference to keep your feet nice and toasty. Adjust your electric thermal socks to either low-temperature mode (40 C/104 F), medium-temperature mode (50 C/122 F), or high-temperature mode (60 C/140 F). You can rely on these heated boot socks to keep your toes comfortable no matter how cold it is. LONG-LASTING UPGRADED BATTERY: The battery-heated socks can last for up to 4 hours on the highest setting and 9 hours on the lowest heat setting, so you don t have to worry about the power running out too soon. With consistent charging, you can even enjoy using your electric heated socks for long periods of time without any problems. Feel free to go on long walks or travel while these electric warm socks keep your feet comfy all the time.