I want to provide a warning about OtherWorldComputing/MacSales memory upgrades for laptops. I installed a chip in my MacBook Pro. You have to leave a special paper sticker on the chip or else the warranty from OWC is void. Apple later repaired my MacBook Pro and found that the chip was defective. They returned the OWC chip without the sticky label. When I questioned Apple repair they said that such chip stickers frequently fall off because the heat of the laptop dries out the adhesive. And, of course, OWC refuses to reimburse me for the memory upgrade because it lacks this sticker. So, my advice is to avoid memory upgrades that require you keep a stick in your laptop.