Amazon.com: OWC 32GB (2 x 16GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S32P) : Everything Else
v-Color 32GB (2 x 16GB) ECC SO-DIMM DDR4 2666MHz (PC4-21300) for NAS Micro Server/Workstation/Compatible with Synology 21 Series 2Rx8 CL19 1.2V (TES416G26D819K-VKC) at Amazon.com
CORSAIR Vengeance 16GB (2 x 8GB) 260-Pin DDR4 SO-DIMM DDR4 2400 (PC4 19200) Notebook Memory Model CMSX16GX4M2A2400C16 - Walmart.com
Crucial 32GB (2 x 16GB) 260-Pin DDR4 SO-DIMM DDR4 2133 (PC4 17000) Laptop Memory Model CT2K16G4SFD8213 Laptop Memory - Newegg.com
Apple 128GB DDR4 LR-DIMM ECC Memory Module Kit (2 x 64GB)
G.Skill Ripjaws 16GB 2 x 8GB DDR4-2666 PC4-21300 CL19 Dual Channel SO-DIMM Memory Kit F4-2666C19D-16GRS - Micro Center
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