Each new replacement air bag is assigned specifically to the vin # of your vehicle. Once the second notice arrives , the dealer has been given the air bag for your car to install. I repeat, any air bags installed prior to a first notice were not upgraded units, but a stock unchanged replacement and are not good. The chemical detonation compound used in the bag has been changed with a structure mod to the unit as well. To get the new unit you must have a second notice of recall.