Mid 2011 Apple iMac 21.5" A1311 i5 2.7GHz 8GB RAM 1TB HD OSX Sierra - DCPS Computer Program
Apple iMac 21.5" A1311 -i3 2.5GHz 4GB Ram 250GB MacOS High Sierra (GRADE B) | eBay
A-Tech for Apple 8GB Kit 2X 4GB PC3-10600 1333Mhz Mac Mini iMac Mid 2011 Mid 2010 Late 2011 MC508LL/A A1311 MC509LL/A MC510LL/A A1312 MC978LL/A MC816LL/A A1347 MC936LL/A Memory RAM at Amazon.com
Install memory in an iMac - Apple Support
32.0GB OWC Memory Upgrade Kit For 2010-2011 Apple iMac
Install memory in an iMac - Apple Support
A-Tech for Apple 8GB Kit 2 x 4GB PC3-10600 Mac Mini iMac MacBook Pro Mid 2010 Late 2011 A1286 MD311LL/A A1297 MC511LL/A A1312 MC309LL/A A1311 MC812LL/A MC813LL/A MC814LL/A MC815LL/A A1347 Memory RAM