Please refer to the size chart in the image to choose your size. [Material composition] Front: 100% nylon / Back/Filling: 100% polyester *This product does not come with a mobile battery or AC adapter. *When using your own battery, please be sure to use a battery that supports "USB output: 5V⎓4.5A / 5V⎓3A / 9V⎓2A / 12V⎓1.5A". *Even if the battery is within the standard, if the USB cable is not plugged in all the way, it may not warm up due to a poor connection. *We recommend Excitech's exclusive battery [model number: EXB01]. *Recommended battery size: Length 141 x Width 68 x Thickness 28 mm *Batteries that exceed this size may not be able to be stored in your pocket. [17 heating vests in the front and back/3 levels of temperature adjustment] The design allows you to feel the warmth in about 3 seconds after turning on the power. You can choose the part you want to warm from four places on the neck, shoulders, front, and back to adjust it. It can be set in three levels: red light = high temperature (approx. 65°C*) / white lamp = medium temperature (approx. 50°C*) / blue lamp = low temperature (approx. 45°C*), and the temperature can be seen at a glance by the color of the button. *The temperature is a reference value based on our own test (room temperature 20°C environment). It depends on the usage environment. [Easy operation 3 steps] 1. Connect the USB cable in the vest inner pocket to the mobile battery (insert the cable firmly until "PD" is displayed on the battery screen). 2. Press and hold the power button on the back of the chest to start. 3. With each short press of the button, it switches from red (hot→ white (medium temperature) → blue (low temperature). You can choose your preferred temperature/place to heat up. (When you want to turn off the power, press and hold the button on the warmed area until it disappears.) ） *As a safety feature, it is designed to automatically switch to medium temperature (white lamp) after a few minutes after reaching high temperature. There is also a slight gap between the plug-in and the main body, but this is a normal specification. [Wide range of sizes] Available in 6 sizes: M, L, XL, 2XL, 3XL, and 4XL. It can be used by both men and women. Please refer to the size chart before ordering. [Package contents] Heat vest body, instruction manual (with warranty card) [Washable] The vest is washable. Be sure to remove the power bank and close the USB cap tightly before washing. *We recommend using a laundry net. *Please refrain from using the dryer. [Japan planning and domestic support support] If you have any questions or issues with the product, please feel free to contact our customer support. *When using your own battery, please use one that supports "USB output: 5V⎓4.5A/5V⎓3A/9V⎓2A/12V⎓1.5A". *This product does not come with an AC adapter