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MemoryMasters 64GB (2 x 32GB) 2666MHz DDR4 PC4-21300 SO-DIMM 260 Pin Memory Upgrade, (2666DDR4S64P), for 2018 Mac Mini (macmini18,1), 2019 27 inch iMac (iMac19,1) and PC laptops at Amazon.com
Crucial 32GB Kit (16GBx2) DDR4 2666 MT/s (PC4-21300) DR x8 SODIMM 260-Pin Memory - CT2K16G4SFD8266 at Amazon.com
DATARAM 64GB (2 x 32GB) 2666MHz DDR4 PC4-21300 SO-DIMM 260 Pin Memory Upgrade for 2018 Mac Mini (macmini18,1), 2019 27 inch iMac (iMac19,1) and PC laptops at Amazon.com