Hynix original 16GB (2 x 8GB), 204-pin SODIMM, DDR3 PC3L-12800, 1600MHz memory module at Amazon.com
QNAP Memory RAM-8GDR3-SO-1600 8GB DDR3-1600 SO-DIMM f/TS-x69/x73 Series/IS-400 Pro Retail 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