OWC Internal SSD DIY Kit for Apple iMac 27" OWCDIDIM27SSD11 B&H
Apple iMac 21.5” SSD Upgrade (2013-2015) HDD To Solid State Drive (SATA) | Step By Step - YouTube
OWC SSD Upgrade Kits for 21.5-Inch iMac (2013 - 2019)
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
iMac late 2015 27'' ssd install for those want to upgrade : r/osx
How to Upgrade iMac Hard Drive (2009, 2010, 2011): EveryMac.com
21.5" iMac Hard Drive SSD Upgrade or old drive replacement 2012-2017 (Including Retina) in 4k - YouTube
How to Upgrade iMac Hard Drive to SSD | Make Your iMac Faster | Step by Step - YouTube
Base model iMac Pro teardown sheds more light on its upgrade potential - 9to5Mac