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
Crucial 4GB Single DDR3 1066 MT/s (PC3-8500) CL7 SODIMM 204-Pin Notebook Memory Module CT51264BC1067 at Amazon.com