ObboMed MF-2305M Far Infrared Carbon Fiber Heated Foot Warmer/Boots/Slippers, USB 5V 10W Auto Off, Size M: (fits Foot up to 41)

Powered by 5V low-voltage USB outlet with the latest carbon fiber heating technology for heating function. Two heating levels With LED power indicator to display heating levels for best using experience: Green light indicates Level I (gentle warmth, 5W), red light indicates Level II (fast warmth, 10W). ^^ Soft sole design for comfy touch, designed with zippers for better wearing comfort and convenience ^^ Two-piece booties designed for providing more mobility than conventional foot warmers; allow users to move more freely in the surrounding area.
*Note: Not suitable for outdoor use. ^^ Heating temperature up to 109F/ 43C, depends on ambient temperature, and accumulated heating time. It takes 5 to 10 minutes to feel warm, longer heating accumulate more warmness. The heater will automatically turn off after 3 hours for users safety. ^^ Include AC 110V-230V to DC 5V, 2.5A USB adapter for steady warmth and better heating. Detachable cable from the shoes or USB from laptops, PCs, and power banks for convenient movement (PS. USB from laptops, PCs only provides half working power (5W), it is not as warm as powered by adapter)