Samsung Laptop Memory 4GB 1Rx8PC3L-12800S-11-13-B4 M471B5173QH0-YK0 at Amazon.com
Samsung original 4GB, 204-pin SODIMM, DDR3 PC3L-12800, ram memory module for laptop ( M471B5173QH0-YK0 ) at Amazon.com
OWC 8GB PC3-12800 DDR3L 1600MHz SO-DIMM 204 Pin CL11 Memory Module Upgrade Compatible with iMac, Mac Mini, and MacBook Pro (OWC1600DDR3S8GB) at Amazon .com