16GB Memory for Apple iMac Retina 5K, 27-inch (2020) DDR4 2666 MHz PC4-21300 RAM | eBay
OWC 32GB (2 x 16GB) PC21300 DDR4 2666MHz SO-DIMMs Memory, Compatible with Mac Mini 2018, iMac 2019 and up, and Compatible PCs, (OWC2666DDR4S32P) at Amazon.com
DDR4 | 2017 iMac | 32GB | SO-DIMM | iMac Memory
Timetec 32GB KIT(2x16GB) Compatible for Apple DDR4 2666MHz / 2667MHz for Mid 2020 iMac (20,1/20,2) / Mid 2019 iMac (19,1) 27-inch w/Retina 5K, Late 2018 Mac Mini (8,1) PC4-21333 /PC4-21300 MAC RAM at Amazon.com
DDR4 | 2019/2020 iMac | SO-DIMM | iMac Memory
A-Tech 64GB Kit (2x32GB) RAM for Apple iMac & Mac Mini (2018, 2019 & 2020) | DDR4 2666 MHz SODIMM PC4-21300 / PC4-21333 260-Pin SO-DIMM Memory Upgrade at Amazon.com