Timetec 16GB KIT(2x8GB) Compatible for Apple DDR3L 1600MHz for Mac Book Pro(Early/Late 2011,Mid 2012), iMac(Mid 2011,Late 2012,Early/Late 2013,Late 2014,Mid 2015), Mac Mini(Mid 2011,Late 2012) MAC RAM at Amazon.com
What Does It Take To Upgrade a 2012 iMac 21.5"?
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
Apple's 2012 iMac: Ready for its close-up (pictures) - CNET
21.5" iMac Has No User-Upgradable RAM; 27" Has Four Accessible RAM Slots - MacRumors
Apple iMac 27" Desktop Core i5-3407S 2.9GHz 8GB RAM 1TB HDD Mojave OS 2012 w/ Keyboard & Mouse
How to: Install RAM in an iMac (2011/2012) - YouTube
NEMIX RAM 16GB Kit (2x8GB Upgrade) DDR3-1600 SODIMM PC3-12800 for Apple MacBook Pro Mid 2012 / iMac Late 2012 / iMac 2013, Late 2014, Mid 2015, Mac Mini Late 2012 at Amazon.com
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
RAM Door for iMac 27 2012 A1419 DIY Parts replacement Internal Parts
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
OWC 8GB (2 x 4GB) PC12800 DDR3L 1600MHz SO-DIMMs Memory Compatible with 2011-2015 iMac, 2011-12 Mac Mini, and 2011-2012 MacBook Pro (Non-Retina Display) Models (OWC1600DDR3S08S) at Amazon.com