iMac i7 Memory Model 11.3 (i5 and i7) 12.1 & 12.2 | Ramjet.com
Adamanta 16GB (2x8GB) Apple Memory Upgrade DDR3L 1600MHz SODIMM Compatible for iMac (Mid 2011, Late 2012, Early/Late 2013, Late 2014, Mid 2015) 2Rx8 CL11 1.35v RAM at Amazon.com
Differences Between Mid-2011 and Late 2012 Aluminum iMac: EveryMac.com
Install memory in an iMac - Apple Support
How to Upgrade/Replace the Main Drive in a 27-inch Apple iMac 2011 (iMac12,2) - YouTube
16GB [4x4GB] DDR3-1333 RAM Memory Upgrade Kit for The Apple iMac 12,2 (27-inch, 2.7GHz, MC813LL/A) Quad-Core Intel Core i5 (Genuine A-Tech Brand) at Amazon.com
Amazon.com: Timetec 16GB KIT(4x4GB) Compatible for Apple DDR3 1333MHz PC3-10600 CL9 for iMac (Mid 2010 27 inch, Mid 2011 21.5/27 inch) SODIMM Memory Module MAC RAM Upgrade for iMac 11,3 / iMac 12,1 / iMac 12, 2 : Electronics
21.5" iMac (Mid 2011) Model ID:iMac12,1 - TransIntl
OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com