OWC DIY Drive Upgrade/Install Kits for Apple iMac Models
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
OWC HDD Upgrade Kit with Tools and Digital Thermal Sensor for all iMac 2011 | eBay
1TB SSUAX PCIe 2.0 x4 SSD Install Kit - Apple iMac 21.5 A1418 Late 2013,Mid 2014 | eBay
Upgrading a 27-inch iMac 5K to 14 terabytes - Replacing the Fusion Drive with both a SSD and an harddisk