BlueBuilt power banks are built by Coolblue and are designed based on our product knowledge and customer feedback. We are so confident that we give you a 5-year warranty. The 10,000mAh power bank can charge your smartphone about 3 times. A larger 20,000mAh power bank, for example, is useful for camping trips. Choose a power bank with fast charging to charge your smartphone or tablet extra fast. Power Delivery works for all Apple products and many Android devices. Quick Charge only works with Android smartphones.