The AMS Lite 4-pin cable is used to connect the A1 mini main unit and the AMS Lite device. It serves two functions: providing power from the A1 mini to the AMS Lite and facilitating communication between the two devices. This enables the A1 mini to control the AMS Lite, allowing it to read information from the filament spool RFID tag and manage the switching/extrusion of multi-color 3D printing consumables.