Samsung RAM Module - 16 GB - DDR4 SDRAM - 2400 MHz DDR4-2400/PC4-19200 - 1.20 V - Non-ECC at Amazon.com
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