A-Tech 4GB DDR3 1600MHz Desktop Memory Module (1 x 4GB) PC3-12800 Non-ECC Unbuffered DIMM 240-Pin 1Rx8 1.5V High Density Single Rank Computer RAM Upgrade Stick at Amazon.com
Kingston Technology 4 GB Memory for Select Apple Imac's and Macbooks Single (Not a kit) 1066 MHz (PC3 8500) 204-Pin DDR3 SO-DIMM KTA- MB1066/4G at Amazon.com