NOTE! Nominal capacity expressed in mAh (milliampere hours) means the sum of all cells that were used in the power bank. The cells used have a voltage of 3.6 - 3.7V, while the standard USB port - 5V, so voltage conversion is necessary, which in turn translates into real capacity. After conversion, it is usually around 65-67% of the original value. This means that for a power bank with a capacity of 12,000 mAh, in fact about 8,000 mAh is available.