Do you mean you want to upgrade your RAM from 2 GB to 4 GB? The best way to figure out what ram you need is to go to this page on Apple's support site to find out what RAM works with your model of MBP. I recently upgraded Macbook ram and found that it works in the newly obsolete (non-unibody) macbook pro. I believe it's PC5300(don't quote me!) and it was about $50 on Amazon for 4GB. Do your research before you buy, RAM comes in a lot of different sizes, and your computer may not support the full 4GB. Hope this helps!