Give yourself an extra 7.5 hours of battery life with the 3000mAh Gobi Heat lithium ion beanie battery. Features: It's works with Crest Women's 2 Zone Heated Beanie It's works with Summit Men's 2 Zone Heated Beanie Up to 7.5 hours of battery life on low heat Works on Crest and Summit beanies Lightweight, compact shape Gobi Heat Additional/Replacement Hat Battery