OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
Memory Upgrades for iMac 21.5-Inch 2019
OWC SSD Upgrade Kits for 21.5-Inch iMac (2013 - 2019)
A-Tech 32GB Kit (4x8GB) RAM for Apple iMac (Late 2012, Late 2013, Late 2014, Mid 2015) | DDR3 1600MHz PC3-12800 SODIMM 204-Pin Memory Upgrade at Amazon.com
Apple iMac 21.5" Late 2013 Core i5 2.7GHz 8GB RAM 1TB HDD MacOS Big Sur 11.5.7 | eBay
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
SOLVED: Need more ram for iMac 21.5 late 2013 - iMac Intel 21.5" EMC 2638 - iFixit
Apple iMac review (21.5-inch, 2015): 4K is optional, faster hard drives shouldn't be | Engadget
16GB KIT 2X 8GB for Apple iMac 2.7GHz 21.5" Late 2013 2.93GHz 27" Late
Apple Mac Memory Ram Upgrades Dublin
iMac | 2.7 GHz Intel i5 | 21.5 Inch | Late 2013 - Techable.com
CMS 16GB (2X8GB) DDR3 12800 1600MHz Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac Core I5 3.4 27-Inch (Late 2013) Me089Ll/A - A7 at Amazon.com
Differences Between 2013/2014 iMacs and Late 2015 iMacs: EveryMac.com
iMac (21.5-inch, 2.8GHz Intel Core i5, Late 2015) | iGotOffer
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
Apple iMac 27-inch (2019) review: Apple iMac 2019 is a millennial trapped in the body of a baby boomer - CNET
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013