USB (FIR) thermal belt for sports, relaxation, and thermal therapy. With far infrared heat, it provides deep warmth and a sense of comfort. Improves blood circulation, reduces muscle pain, and helps muscles recover. Patented technology with special FIR rubber heating element for even heat distribution. Multifunctional, can be used with 5V external battery or USB power source. 3-level temperature control for personalized adjustment. Easy to clean and machine washable up to 45°C. Size: length 100 cm + extension, width 15 cm - 20 cm.