if you want to be certain that the SSD you buy will work, buy whatever OWC (MacSales.com) recommends for your computer. Use the correct size and type of screwdrivers. Use static precautions. Set up an egg carton or the like, labelled with size/location of each screw you plan to remove/replace. There is not much visual difference, often the screws are the same but for a tiny difference in length, but the wrong screw in some spots can cause $£¥? trouble.