64GB (2x32GB) NEMIX RAM Memory for 2019 Apple iMac 27 inch Retina 5K (iMac19,1 A2115), 2018 Apple Mac Mini (Macmini8,1 A1993) System Specific Memory - Newegg.com
OWC 512GB 2666 MHz DDR4 LRDIMM Memory Upgrade Kit
64GB Memory Upgrade for 2019-2020 Apple iMac (27-inch)
OWC Confirms New Low-End 27-inch iMac Can Be Fitted With 64GB RAM - MacRumors
64GB Memory Upgrade for 2019-2020 Apple iMac and 2018 Mac mini
64GB (4X 16GB) DDR4 2400MHz PC4-19200 SO-DIMM RAM Memory Upgrade for 2017 iMac 27 inch with 5K Retina Display (PARTS-QUICK) - Walmart.com
Install memory in an iMac - Apple Support
Micron 64GB (2 x 32GB) DDR4 2666MHz SODIMM Memory Upgrade Kit Compatible with 27 inch iMac (iMac19,1 iMac20,1 iMac20,2) - Walmart.com