The product does not include power banks. You need to use 5V.2A 20000Ah or more power bank. We are Asian size, 2-3 sizes smaller than European size. Please choose the correct size according to our size Press and hold the buttons for 3 seconds at the same time, the two buttons will turn red at the same time to work, and only one button will turn red for regional heating Size Info: Our Size Chart show base on Asian size . Usually EU Size XS=Asian size M EU Size S = Asian Size L EU Size M = Asian Size XL EU Size L = Asian Size 2XL EU Size XL = Asian Size 3XL EU Size XXL=Asian Size 4XL We are Asian size, 2-3 sizes smaller than European size. Please choose the correct size according to our size chart and height/weight...1.1 Minute fast heat, dispelling cold and keeping you warm. 2.Set the temperature you want to respond to a variety of environments. 3.A button to heating, three stall temperature control, intelligent heating. 4.It can be washed by machine and can be washed by hand. Do not wring it by hand. 5.General USB interface power supply, longer service life, anti water splashing and washable. 6.The fashion is warm, comfortable and breathable, and its a good partner for your winter going out.: 1.Style: Sleeveless Vest 2.Material: Polyester 3.Color: black/blue 4.Size: S/M/L/XL/2XL/3XL/4XL/5XL/6XL 5.Power Supply: 5V/2A Mobile Power(Not Included) 6.Temperature Shift(Manual adjustment) 7.Warm:45 (Red Light) 8.Comfort:35 (White Light) 9.Energy Saving:25 (Blue Light) Packing list Package Contents: 1 * Heating Vest.