Stay warm on brisk, fall days with the Gerbing 7V Battery Heated Base Layer Long-Sleeve T-Shirt for Men. Constructed of a soft, flexible polyester/spandex blend, this base layer shirt features multiple microwire heating panels in the chest and back for lasting warmth where it matters most, while simple touch-button controls make for easy activation and deactivation. Operating on a rechargeable 7V 3400mAH lithium battery, this shirt is machine washable for lasting performance. Estimated battery life: 100% power: 2+ hours; 75% power: 3+ hours; 50% power: 5+ hours; 25% power: 8+ hours. Includes USB charging cord. Machine wash. Imported. Manufacturer style #: GER-BLS. 92% polyester/2% spandex Multiple microwire heating panels Simple touch-button controls Rechargeable 7V 3400mAH lithium battery Up to 8+ hours of operation (lowest setting)