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
Crucial 16GB Kit (8GBx2) DDR4 2400 MT/s (PC4-19200) DR x8 SODIMM 260-Pin Memory - CT2K8G4SFD824A at Amazon.com