When you need serious warmth, you need the Gerbing 7V Battery-Heated Base-Layer Long-Sleeve Shirt for Ladies. Featuring Microwire heat technology with built-in heating panels strategically places on the chest and upper back, this women's shirt has 4 levels of heat that are accessible at the touch of a button to provide up to 8 hours of battery-powered warmth. The next-to-skin fit means you can add a layer over this shirt to trap the heat, ensuring you stays warm longer. The easy-to-access touch-button control on the chest mean it's easy to adjust the temperature. Made from 92% polyester/8% spandex. The Gerbing 7V Battery-Heated Base-Layer Long-Sleeve Shirt for women includes a rechargeable 7-volt battery and a wall charger. Manufacturer's lifetime warranty. Machine wash. Imported.Manufacturer model #: GERBLS-7V-W-B. 92% polyester/8% spandex 4 levels of heat controlled by an easy-access button on the chest Provides up to 8 hours of battery-powered warmth Microwire heat technology with heat panels in the chest and upper back Close-to-skin fit allows easy layering over the top Includes a rechargeable battery and wall charger