Opened up 2012 21.5 iMac for SSD upgrade. | MacRumors Forums
late 2012 - 9to5Mac
What Does It Take To Upgrade a 2012 iMac 21.5"?
NEMIX RAM 32GB Kit (4x8GB 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
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
Timetec Hynix IC Apple 8GB DDR3L 1600MHz PC3L-12800 SODIMM Memory upgrade For MacBook Pro 13-inch/15-inch Mid 2012, iMac 21.5-inch Late 2012/ Early/ Late 2013 (8GB) - Walmart.com