A friend of mine purchased this deck from a dealer today. The dealer said that they were so behind on installs that it would be a week or two before they could get to him.He didn't want to wait, So i installed the deck for him,my question is,what is the metal box with the labels that say to keep away from spkr and pwr wires for. I had mine installed by the dealer and i never knew that there was a box this size behind the radio.Thanks