OEM plug. OEM speakers usually do not have positive and negative terminals marked. For my 1998 A6, 30v 2.8, the solid black wire is negative. The Alpines have a small and large clip one for neg, one for positive, so you need to get these identified before splicing the wires. This plug is thrown away later. After removing the speaker, I plugged it back in, touch the wires to a D battery. If the speaker moves up you have touched the neg to neg on the battery and pos to pos. If it moves down reverse and you should see it move up.