You need a supply unit to power your Philips Avent Essential breast pump. The breast pump comes with a USB cable that you can connect to the device but does not come with a supply unit.
It is important to use only a supply unit with an output of 5V with at least 1A. Connect your assembled breast pump to the supply unit and plug it into a power source. Please note that this breast pump is not rechargeable and must be connected to a power source during the entire session.
Once you have finished using the breast pump, unplug it from the power source immediately.