keep Your Body And Hands Warm: Qualified Carbon Fiber Heating Elements With 3 Heating Levels To Generate Consistent Heat For 4 Core Body Parts, Including Your Neck, Back, Abdomen, And Waist, Helping To Maintain Body Warmth.NOTE:Operation: When powerbank connected to the vest, it will be heating. When powerbank was disnectted to the vest, it will stop heating.A 10000mah Power Bank Offers Up To 8 To 10 Hours Of Warmth On Average(lasting Period Can Be Vary Depending On Different Types Of Power Bank); Power Bank Is Not Included In Our Product.overheat Protection: Implanted Sensor Will Be Triggevermelho To Terminate Heating Immediately If, For Any Reasons, The Heating Areas Internal Temperature Exceeds 150f. Guarantee Your Safety In Any Occasions.