OWC Internal SSD DIY Kit for Apple iMac 27" OWCDIDIM27SSD11 B&H
Upgrading a 27-inch iMac 5K to 14 terabytes - Replacing the Fusion Drive with both a SSD and an harddisk
maxupgrades.com: Single SSD Drives kit for iMac 27 inch 2012 Models with SATA Blade SSD Module / Heatsink/ Power Cable and DATA Cables for [SSD + HDD] with iMac Adhesive LCD Tape
SSD Upgrades for Apple iMac 27-Inch Late 2013 - 2019
SSD Upgrade Kits for 27-Inch iMac (2012 - Early 2013)
661-03563 Apple 1TB SSD Flash Storage for iMac 27" Late 2015
Apple 27-inch iMac 2020 review | Macworld
DIY Bundle - 2TB OWC 6G SSD and HDD Kit for 27-Inch iMac