Baseus Mini CU Power Bank 10000 mAh (PPALL-KU01) – Black is ultra thin (about the thickness of a standard pencil) and boasts 2 USB 2.1A ports and a Micro USB socket.
Its simple and elegant design makes it perfect for travelling and with 9 built in safety features and aviation standard compliant this really is an easy choice if you are looking for something not overly complicated, but easy to carry and powerful.