HPE RAM Memory 1 x 64GB DDR4 SDRAM 64 DDR3 2400 726724-B21 at Amazon.com
Crucial RAM 64GB Kit (2x32GB) DDR4 3200MHz CL22 (or 2933MHz or 2666MHz) Laptop Memory CT2K32G4SFD832A at Amazon.com
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
Corsair CMK64GX4M4A2666C16 Vengeance LPX 64GB (4x16GB) DDR4 2666 C16 Desktop Memory Kit for DDR4 Systems at Amazon.com
A-Tech 64GB Kit (2x32GB) RAM for Apple iMac & Mac Mini (2018, 2019 & 2020) | DDR4 2666 MHz SODIMM PC4-21300 / PC4-21333 260-Pin SO-DIMM Memory Upgrade at Amazon.com