MICRON 4GB DDR4 3200MHz PC4-25600 1.2V 1R x 16 SODIMM Laptop RAM Memory Module MTA4ATF51264HZ-3G2J1, OEM Package 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