64GB Server RAM Module Kit | DDR4 2666MHz | Integral Memory
OWC 64GB (4 x 16GB) PC21300 DDR4 2666MHz SO-DIMMs Memory Compatible with Mac Mini 2018, iMac 2019 and up, and Compatible PCs (OWC2666DDR4S64S) at Amazon.com
HPE 815101-B21 64GB 4DRX4 DDR4-2666MHZ LR Smart Memory
Micron 64GB (2 x 32GB) DDR4 2666MHz SODIMM Memory Upgrade Kit Compatible with 27 inch iMac (iMac19,1 iMac20,1 iMac20,2) - Walmart.com
Cisco 64GB DDR4-2666-MHz LRDIMM/PC4-21300/4R/x4 » Vista IT Group
OWC 64GB (2 x 32GB) PC21300 DDR4 2666MHz SO-DIMMs Memory Compatible with Mac Mini 2018, iMac 2019 and up, Dell, HP, Lenovo, ASUS and Compatible PCs (OWC2666DDR4S64P) at Amazon.com