Crucial 16GB Single DDR4 2666 MT/s (PC4-21300) DR X8 SODIMM 260-Pin Memory - CT16G4SFD8266 - Walmart.com
OWC 32GB (2 x 16GB) PC21300 DDR4 2666MHz SO-DIMMs Memory, Compatible with Mac Mini 2018, iMac 2019 and up, and Compatible PCs, (OWC2666DDR4S32P) at Amazon.com