ADDAO Rechargeable Double-Sided Hand Warmer and 3000MAH/4000MAH/4500MAH Power Bank/External Battery Pack Charger For Cell Phones and Mobile iPhone 8/7/6/5c/5s/5/4 Galaxy S5/S4/S3 Upgraded battery capacity of 4000mah. Longer heating hours. Wrapped by aluminum shell this digital hand warmer is a double-side warmer.Using sophisticated ceramic heating component Inspires from from Macaron, a word famous French dessert,fashion and delicious! The warmer will automatically start heating for 5 minutes every time you breathe on the blow hole Small size of 69mm diameter.To be easily kept in either pocket or bag or hold in your hand.Comfortable on hand.Fit for hand size.Handy size with sufficient power to charge your phones.Enough for daily use