Amazon.com: OWC SSD Upgrade Kit for 2011 21.5-inch iMacs, Mercury Electra 250GB 6G SSD, 18" SATA III 6Gbps Data Cable, Installation Tools and iMac Screen Adhesive Tape Set : Electronics
2017 21.5-inch 4K iMac memory upgrade kit includes 32GB of RAM, tools to take it apart | AppleInsider
Apple iMac 21.5” SSD Upgrade (2013-2015) HDD To Solid State Drive (SATA) | Step By Step - YouTube
iMac Intel 21.5" Retina 4K Display (2017) RAM and SATA Hard Drive Upgrade - iFixit Repair Guide
Apple iMac SSD Upgrade — Epoch IT: Computer Repair Allentown, IT Services, Managed IT, Allentown PA, Lehigh Valley, Bethlehem, Easton
OWC SSD Upgrade Kits For 21.5-Inch iMac 2010
How to Upgrade iMac Hard Drive (2009, 2010, 2011): EveryMac.com
2013 iMac teardowns reveal SSD slots, soldered-in CPU in the 21.5” model | Ars Technica
iMac 21.5" (2012-2017) 🖥 Hard Drive Replacement/SSD Upgrade - YouTube