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
How to Upgrade the 3.5-inch Main Drive in a 21.5-inch iMac Mid 2010 (Updated) - YouTube
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OWC DIY Drive Upgrade/Install Kits for Apple iMac Models
Amazon.com: OWC 2.0TB HDD Upgrade Kit Compatible With 2009-2010 iMacs, Includes: Thermal Sensor, Tools, 2.0TB Hard Drive : Electronics