OWC 12GB (8GB+4GB) PC3-12800 DDR3L 1600MHz SO-DIMM 204 Pin CL11 Memory Upgrade Kit Compatible with iMac, Mac Mini, and MacBook Pro (OWC1600DDR3S12S) 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
4GB DDR3 1600Mhz Laptop Memory Ram+Cooling Vest SO-DIMM PC3 12800 DDR3L 1.35V Memoria Sdram for Laptop Notebook - Walmart.com