iMac 21.5" Mid 2011 How To Change/Upgrade Your Ram For Better Performance 2014 - YouTube
32.0GB OWC Memory Upgrade Kit For 2010-2011 Apple iMac
Apple iMac Mid 2011 21.5-inch (iMac12,1), MC812LL/A, EMC: 2428 Memory
Timetec Hynix IC 32GB KIT(4x8GB) Compatible for Apple 27 inch Mid 2010 21.5/ 27 inch Mid 2011 iMac DDR3 1333MHz PC3-10600 CL9 204 Pin SODIMM Upgrade for iMac 11,3 iMac 12,1 iMac 12, 2 (32GB KIT(4x8GB)) - Newegg.com
Amazon.com: Timetec 32GB KIT(4x8GB) 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
Apple Launching Pilot Program Allowing Repairs of Soon-to-Be Vintage Mid 2011 iMac in United States - MacRumors
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
How to Upgrade iMac RAM (21.5" and 27" Aluminum): EveryMac.com
Amazon.com: Timetec 8GB KIT(2x4GB) Compatible for Apple DDR3 1333MHz PC3-10600 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) RAM Upgrade : Electronics