This is a top case assembly for the 17" MacBook Pro. This is the piece that includes the trackpad and power button. To determine which top case 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 A1212, then you need to pick the option below with A1212 in the description.