Crucial RAM 8GB DDR4 3200MHz CL22 (or 2933MHz or 2666MHz) Laptop Memory CT8G4SFRA32A at Amazon.com
Amazon.com: Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3 1333MHz PC3-10600 CL9 for Mac Book Pro (Early/Late 2011 13/15/17 inch), iMac(Mid 2010, Mid/Late 2011 21.5/27 inch), Mac Mini(Mid 2011) MAC RAM Upgrade :
Hynix HMT451S6AFR8A-PB 4GB PC3-12800 DDR3-1600MHz non-ECC Unbuffered CL11 204-Pin SoDimm 1.35V Low Voltage Single Rank Memory Module at Amazon.com
TEAMGROUP Elite DDR4 64GB Kit (2 x 32GB) 2666MHz (PC4-21300) CL19 Unbuffered Non-ECC 1.2V UDIMM 288 Pin PC Computer Desktop Memory Module Ram Upgrade - TED464G2666C19DC01 at Amazon.com