This unit, having the capacity of 20,000 mAh, has twice the capacity of most other units. The dimensions are 2.5 x 5.5 x 1.2 inches approximately. It supports Qualcomm Quick Charge protocol using the proper internal circuitry. I believe it can charge 1 or 2 devices while being simultaneously charged itself. This is my new favorite power bank. I am sure you would like it too.