Patriot Memory Viper Series DDR4 8GB 2400MHz (PV48G240C5S)
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
Patriot Viper 4 Series Extreme Performance DDR4 16GB (2 X 8GB) 3200MHz Kit (PC4-25600) PV416G320C6K at Amazon.com