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Factory Original 64GB (2x32GB) Memory Upgrade for 2020 & 2019 Apple iMac 27" w/Retina 5K Display & 2018 Apple Mac Mini DDR4 2666Mhz PC4-21300 SODIMM 2Rx8 CL19 1.2v RAM Adamanta at Amazon.com
24" iMac with Retina 4.5K display Apple M1 8GB Memory 256GB SSD (Latest Model) Pink MJVA3LL/A - Best Buy
Memory Upgrades for iMac 27-Inch (2012 - Mid 2015)
Amazon.com: OWC 8GB (2 x 4GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S08P) : Everything Else
32.0GB OWC Memory Upgrade Kit For 2010-2011 Apple iMac