Upgrade your iMac with OWC, 2017 4K Retina Edition
2017 iMac SSD upgrade & Speedtest - YouTube
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Amazon.com: USB C 3.2 Gen2 MacBook SSD Enclosure for Apple Flash SSDs 12+16 PIN MacBook Pro MacBook Air Mac Pro iMac from 2013 to 2017, with Adapter to Support M.2 NVMe SSDs (