16GB (2x8GB) DDR3-1600MHz PC3-12800 Non-ECC UDIMM 2Rx8 Desktop Memory Module by NEMIX RAM at Amazon.com
OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
16GB (2x8GB) DDR3 RAM PC Module kit 1600MHZ, by Integral