Hello,
I own iMac 21,5 late 2012:
https://everymac.com/systems/apple/imac/specs/imac-core-i5-2.7-21-inch-aluminum-late-2012-specs.html
After HDD failure I am going to replace it by SSD (Samsung SSD 850 EVO 2.5" SATA III 250 GB).
If opening the iMac to replace HDD by SSD, I would like upgrade...