Mind telling why the SSD that's built for a Mac by OWC, that works, is not for you? Instead you want to put in a module built for a PC that doesn't work reliably with a Mac. Now you're talking to someone that fits the adage 'If you can't dazzle them with brilliance, baffle them with BS'. If the 21.5-Inch 'Late 2012' or 'Early 2013' iMac models were configured with an SSD or a 'Fusion Drive' at the time of purchase, the SSD module is connected via a dedicated PCIe connector and another SSD can be installed in its place. Unfortunately, if the system only was configured with a hard drive, the needed connector is not present on the motherboard and there is not a way to add a PCIe-based 'blade' SSD afterwards.
Msata Ssd Connector
SATA III 6Gb/s SSD230,SATA III 6Gb/s SSD220,SATA III 6Gb/s SSD370,SATA III 6Gb/s SSD360,SATA III 6Gb/s SSD340,PCIe SSD 110S,M.2 SSD 400S,M.2 SSD 600,M.2 SSD 800S,M.2 SSD 420S,M.2 SSD 430S,M.2 SSD 820S,M.2 SSD 830S,JetDrive™ 855,JetDrive™ 850,JetDrive™ 825,JetDrive™ 820,JetDrive™ 725,JetDrive™ 720,JetDrive™ 520,JetDrive™ 500,JetDrive™ 420,mSATA SSD 370,mSATA SSD 230S,2.5. Thunderbolt 3 enclosures with M.2, Mac disable the M.2 drivers for the third party (typical Mac OS). But for 2.5', 3.5' these are every where ranges from JBOD, Hardware RAID a 4 drives to 256 drives (SAS Option).