I recently purchased 2011 21.5 iMac (Mid-2011) and I'm obsessed. : r/mac
Install memory in an iMac - Apple Support
21.5” mid-2011 iMac wires? Finally trying to upgrade my RAM and these wires are blocking the slot — did get an iMac with poor build quality? What can I do? : r/mac
iMac 21.5" Mid 2011 How To Change/Upgrade Your Ram For Better Performance 2014 - YouTube
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 : Amazon.com.au: