The Battery inverter has a 12V "cigarette lighter"-type plug and a DIN connector to feed a programmer/tester. An optional cable has two battery clips and a cigarette-lighter type socket to fit directly to 12V battery terminals. It allows a programmer/tester to be used in the field on a disconnected decoder/DIAS, without needing to take it back to the workshop. The actual programmer/tester is not included and must be bought separately.