Adamanta 64GB (2x32GB) Memory Upgrade for 2020 Apple iMac 27" w/Retina 5K Display, 2019 Apple iMac 27" w/Retina 5K Display, 2018 Apple Mac Mini DDR4 2666Mhz PC4-21300 SODIMM 2Rx8 CL19 1.2v DRAM
How to Upgrade/Replace the Memory in a 21.5-inch iMac (2019)
Can you upgrade the RAM in the 27-inch iMac? | iMore
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET