Alternating current (AC) adapters are used to power or charge many common electronic devices, such as mobile phones, laptop computers, or external hard drives. An AC adapter changes AC power from an electrical outlet into the type of power or voltage that an electronic device needs to work. Typically, each device has a designated adapter that is pre-set to the proper voltage conversion. For this reason, among others, AC adapters generally are not interchangeable.
ACAD is the name of the adapter.