iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
Adamanta 16GB (2x8GB) 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 1Rx8 CL19 1.2v DRAM