... , its carbon content is as more as 90%.When USB Warm Pad is energized,the carbon material will convert electric energy ... possiple(conversion rate is about 98%),as well as warm up fast. Furthermore,USB Warm Pad has a good endurance ability against high ... and scapulohumeral periarthritis.3. Link power by USB,this low-voltage power supply is absolutely safe and convinent.Pictures: USB Warm Cushion