OWC SSD Upgrade Kits for 21.5-Inch iMac (2013 - 2019)
Upgrade SSD Apple iMac 21.5 slim A1418
iMac 2013 (and later) with NVME SSD? | MacRumors Forums
Apple iMac 2013 (Late) 21.5-inch (iMac 14,3) SSD ,Ram & OSX Upgrades - ZD Laptop Service Centre
I got a FREE 2013 iMac 21.5 with internal upgrades including Samsung evo ssd and 16gigs of ram. Then used open legacy patcher to install Mac OS Venture 13.5 beta. : r/osx
Amazon.com: Sintech M.2 nVME SSD Adapter Card Upgrade Kits,Compatible for MacBook Air(2013-2017 Year) and MacBook PRO(Late 2013-2015 Year,iMac : Electronics
How to Upgrade/Replace the PCIe SSD in a 21.5-inch iMac (Late 2013) iMac14,1 iMac14,3 - YouTube
iMac (21.5-inch, Late 2013) 500GB SSD Upgrade - NiwTech