This is a bottom pan assembly for the 17" Powerbook G4 Aluminum. To determine which bottom pan you need, look on the bottom of your machine. In the block of text that starts... "Designed by Apple in California...Model Number", the model number of your machine is the type of bottom pan you need to order. So, for example, if the model # on the bottom of your machine is A1013, then you need to pick the option below with A1013 in the description..