The GP28 (10,000mAh) carry enough juice to charge all your devices without trouble. Their carbon fiber texture and rounded ergonomic shape make up for two power banks that are easy to hold and carry. 2 USB Type-A outputs allow you to charge up to 2 devices simultaneously. Additionally, their built-in digital LED display show clearly the percentage of remaining battery level, so you won't have to worry about running out of charge ever again.