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
A-Tech 4GB DDR3 / DDR3L 1600MHz Desktop Memory Module (1 x 4GB) PC3-12800 Non-ECC Unbuffered DIMM 240-Pin 1Rx8 1.35V Low Voltage Single Rank Computer RAM Upgrade Stick at Amazon.com
4GB (1x4GB) DDR3-1600MHz PC3-12800 2Rx8 SODIMM Laptop Memory by NEMIX RAM at Amazon.com