8GB DDR4 2666 2667 SODIMM Memory RAM Upgrade for APPLE MAC MINI Late 2018 A1993 | eBay
OWC 16GB (2 x 8GB) PC21300 DDR4 2666MHz SO-DIMMs Memory Compatible with Mac Mini 2018, iMac 2019 and up, and Compatible PCs (OWC2666DDR4S16P) at Amazon.com
Crucial 16GB DDR4-2666 SODIMM Memory for Mac | CT16G4S266M | Crucial.com