Simmtec 32GB RAM for Apple iMac 2019 & 2020, Mac Mini 2018 & 2020 | DDR4 2666MHz | eBay
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
Can you upgrade the RAM in the 27-inch iMac? | iMore
iMac 27-Inch With 5K Retina Review 2018 - Rating Apple's New iMac With 5K Retina Display