PNY Performance 8GB DDR4 DRAM 2666MHz (PC4-21300) CL19 (Compatible with 2400MHz or 2133MHz) 1.2V Notebook/Laptop (SODIMM) Computer Memory RAM – MN8GSD42666 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