Apple MC309LL/A 21.5 inch iMac Core i5 2.5 GHz 4GB RAM 500GB HDD Mid-2011 | Recycledgoods.com
A-Tech 4GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010, Mid 2011, Late 2011), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
Used Apple iMac 21.5" Mid 2011 i5-2400S 4GB DDR3 RAM 500GB HDD El Capitan Tested | eBay
A-Tech 4GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010, Mid 2011, Late 2011), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
Apple iMac 2011 Memory 4GB DDR3 1333MHz PC3-10600 204-Pin
Apple iMac 21.5-inch Mid 2011 2.5GHz Intel Core i5 (MC309LL/A) – UNICOM, Inc.
A-Tech 4GB RAM for Apple MacBook Pro (Early/Late 2011), iMac (Mid 2010, Mid 2011, Late 2011), Mac Mini (Mid 2011) | DDR3 1333MHz PC3-10600 204-Pin SODIMM Memory Upgrade Module at Amazon.com
Apple 21.5" iMac All in One Desktop Computer Core i5 4GB Ram 500GB HD OS High Sierra and WIFI Keyboard And Mouse - GRADE B
iMac 27" Specs and Monitoring - MC814-025A
Memory Upgrades for Apple iMac 2011 Up to 32GB
iMac RAM Models 11.3 (i5 and i7 only) to 12.2 (8GBx4) | MacMemory.com
OWC 16.0GB (4 x 4GB) 1333MHz 204-Pin DDR3 SO-DIMM PC3-10600 CL9 Memory Compatible with iMac (OWC1333DDR3S16S) at Amazon.com
Apple iMac 21.5" All-in-One Desktop Computer i3 3.07GHz 4GB Ram 500GB Mac OS High Sierra w/ Keyboard & Mouse - GRADE B
iMac 2011 A1311 21.5 Inch Intel Quad Core i5 2.7GHz 4GB RAM 500G HDD Os Catalina | eBay
4GB PC10600 DDR3 1333MHz SO-DIMM Memory Compatible with 2011 MacBook Pro, Mid 2010/2011 21.5" & 27" iMac Models, 2011 Mac Mini (OWC1333DDR3S4GB) at Amazon.com