SK Hynix 4GB 1Rx8 PC4-17000 DDR4-2133 1.2volt CL15 260 Pin Sodimm Memory p/n HMA451S6AFR8N-TF at Amazon.com
Amazon.com: OWC 8GB (2 x 4GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S08P) : Everything Else
Axiom Memory Solutionlc 4gb Ddr4-2133 Ecc Udimm at Amazon.com
Kingstоn 8GB KIT(2 x 4GB) DDR4 3200MHz PC4-25600 Non-ECC Unbuffered 260-Pin SoDimm OEM Laptop Memory KCDT82-MIE at Amazon.com