64GB (2x32GB) DDR4 2666 PC4-21300 SODIMM Laptop Memory by NEMIX RAM at Amazon.com
Crucial Memory Bundle with 32GB (2 x 16GB) DDR4 2666MHz SODIMM Upgrade kit CT2K16G4SFD8266 Compatible with iMac Retina 5K 27-inch 2019 (iMac19,1) and Mac Mini 2018 (Macmini8,1) at Amazon.com