OLOy DDR4 RAM 64GB (2x32GB) 2666 MHz CL19 1.2V 260-Pin Laptop Gaming SODIMM Upgrade for 2019/2020 iMac 27-inch with Retina 5K Display Late 2018 Mac Mini (MD4S322619MZDC) at Amazon.com
64GB Kit 4x16GB DDR4-2400 PC4-19200 ECC SODIMM 2Rx8 Memory Upgrade by NEMIX RAM at Amazon.com
Corsair Vengeance Performance SODIMM 64GB (2x32GB) DDR4 3200MHz CL22 Unbuffered for AMD Ryzen 4000 Series Notebooks Memory - Black at Amazon.com
v-Color 64GB (2 x 32GB) ECC SO-DIMM DDR4 2666MHz (PC4-21300) for microservers, workstations, Networking Platforms and Embedded Systems 2Rx8 CL19 1.2V (TES432G26D819K-VC) at Amazon.com
Crucial RAM 64GB Kit (2x32GB) DDR4 3200MHz CL22 (or 2933MHz or 2666MHz) Laptop Memory CT2K32G4SFD832A at Amazon.com