NEMIX RAM 16GB Kit (2x8GB Upgrade) DDR3-1600 SODIMM PC3-12800 for Apple MacBook Pro Mid 2012 / iMac Late 2012 / iMac 2013, Late 2014, Mid 2015, Mac Mini Late 2012 at Amazon.com
Memory Upgrades for iMac 21.5-Inch 2012 - Late 2013
How to upgrade RAM iMac late 2013 21.5inch - break & fix MOVIE - YouTube
Apple iMac 21.5-inch and 27-inch (Late 2013) reviews | Macworld
Apple iMac 2013 (Late) 21.5-inch (iMac 14,3) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre
OWC's Latest Upgrade for New Apple 2013 iMac 27” Expands Memory To 32GB, Offering Significant Savings Over Stock Apple Configurations
iMac Late 2013 21.5 SSD Upgrade - YouTube
Apple iMac 21.5" Late 2013 Core i5 2.7GHz 8GB RAM 1TB HDD MacOS Big Sur 11.5.7 | eBay