Arch Memory Certified for Apple 4 GB (1 x 4 GB) 204-Pin DDR3 So-dimm for MacBook Pro Mid-2009 Models MC226LL/A MC226LL/A RAM 1 x 4GB DDR3-1066 PC3-8500 204Pin Sodimm 1.5v Dual Rank (2Rx8) 1066MHz Arch Memory is a Registered Trademark of Arch Computer, LLC Lifetime Replacement Warranty Included