Apple Memory Module 16GB DDR4 2666MHz SO-DIMMS (2x8GB) - Apple
OWC 128GB (4 x 32GB) 2666MHz DDR4 PC4-21300 SO-DIMM 260 Pin Memory Upgrade, (OWC2666DR4S128S), for 2019 27 inch iMac (iMac19,1) and PC laptops - Newegg.com
Timetec 32GB Compatible for Apple DDR4 2666MHz for Mid 2020 iMac (20,1/20,2) / Mid 2019 iMac (19,1) 27-inch w/Retina 5K Display, Late 2018 Mac Mini (8,1) PC4-21333 / PC4-21300 SODIMM MAC RAM Upgrade at Amazon.com
Crucial 16GB (2 x 8GB) DDR4 2666MHz SODIMM Memory Upgrade Kit CT2K8G4SFS8266 Compatible with iMac Retina 5K 27-inch 2019 (iMac19,1) and Mac Mini 2018 (Macmini8,1) - Walmart.com
16GB Memory Upgrade for 2019-2020 Apple iMac or 2018 Mac mini
32GB DDR4-2666MHZ Laptop Memory For Apple 2019 iMac 27-inch w/Retina 5K Display | eBay
128GB (4 x 32GB) DDR4-2666MHz PC4-21300 SO-DIMM Memory for Apple 27" iMac with Retina 5K Display Mid 2020 (iMac 20,1 iMac 20,2) by NEMIX RAM - Newegg.com
Timetec 32GB Compatible for Apple DDR4 2666MHz for Mid 2020 iMac (20,1/20,2) / Mid 2019 iMac (19,1) 27-inch w/Retina 5K Display, Late 2018 Mac Mini (8,1) PC4-21333 / PC4-21300 SODIMM MAC RAM Upgrade at Amazon.com
Timetec 32GB DDR4-2666 SODIMM For Mac - Timetecinc.com - Memory of Lifetime and Easy Upgrades