Ram memory 4GB (1 x 4GB) DDR3 PC3-12800,1600MHz, 204 PIN SODIMM for laptops 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
HYNIX - IMSOURCING SK 4GB DDR3 SDRAM Memory Module - for Desktop PC, Workstation - 4 GB - DDR3-1600/PC3L-12800 DDR3 SDRAM - 1600 MHz - CL11-1.35 V - Non-ECC - Unbuffered - 240-pin - DIMM at Amazon.com