Ram memory upgrades 8GB kit (4GBx2) DDR3 PC3 10600 1333Mhz for latest 2010 & 2011 Apple iMac's and 2011 Macbook Pro's Module Size: 8GB Kit (4GBx2) Package: 204-pin SODIMM Feature: DDR3 PC3-10600 Specs: DDR3 PC3-10600 , CL=9 , Unbuffered , NON-ECC , DDR3-1333 , 1.35V , 512Meg x 64 Lifetime warranty. Scroll down to see compatible models. Please, make sure your Mac supports 4GB DDR3 ram, 1333MHz speed.How to find memory spec. on your Mac?On your Mac screen find and click Apple icon located in left hand side upper corner and chose " About this Mac ". Click " More info ". In the Contents section on the left side of the screen, click " Memory " See memory type and memory speed- make sure, yours is DDR3, 1333MHz.