IF YOU ARE BUYING OR SELLING A CD CAR STEREO SYSTEM FOR A 2001AND ABOVE MODEL DATE, PLEASE TAKE NOTE THAT MOST OF THESE SYSTEMS HAVE SECURITY LOCK FEATURES ON THEM THAT REQUIRE A DE-CODING FORMAT WHICH CAN COST BIG $$. HOWEVER, IF YOU HAVE A NERD IN YOUR HOUSEHOLD LIKE I HAVE, YOU MAY BE ABLE TO REMOVE THE MODULE FROM ONE UNIT AND INSTALL IT INTO ANOTHER UNIT PROVIDING IT IS THE SAME MAKE AND MODEL. OUR PROBLEM WAS THE CD PLAYER WAS LOCKED UP IN OUR FACTORY UNIT.WE WON AN AM-FM CD UNIT ON EBAY FOR $30.00 ...HOOKED IT UP...NOTHING. THEN WE REMOVED THE CD MODULE UNIT FROM OUR WINNING MODEL,INSTALLED IT INTO OUR FACTORY UNIT AND....WOW! THIS SAVED US $600.00!!