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
SanDisk Professional 1TB PRO-BLADE SSD Mag SDPM1NS-001T-GBAND
SOLVED: Can I add a blade SSD to my system? - iMac Intel 21.5" EMC 2544 - iFixit