Kingston Value RAM 4GB 1333MHz PC3-10600 DDR3 Non-ECC CL9 SODIMM SR X8 Notebook Memory (KVR13S9S8/4) at Amazon.com
OWC 4GB PC12800 DDR3L 1600MHz SO-DIMM Memory Compatible with 2011-2015 iMac, 2011-12 Mac Mini, and 2011-2012 MacBook Pro (Non-Retina Display) Models (OWC1600DDR3S4GB) at Amazon.com
Samsung original 4GB, 204-pin SODIMM, DDR3 PC3L-12800, ram memory module for laptop ( M471B5173QH0-YK0 ) at Amazon.com
Amazon.com: Crucial 4GB Single DDR3/DDR3L 1600 MT/s (PC3-12800) SODIMM 204-Pin Memory For Mac - CT4G3S160BM : Everything Else