Crucial Memory Bundle with 32GB (2 x 16GB) DDR4 2666MHz SODIMM Upgrade kit CT2K16G4SFD8266 Compatible with iMac Retina 5K 27-inch 2019 (iMac19,1) and Mac Mini 2018 (Macmini8,1) at Amazon.com
Crucial 8GB DDR3L-1600 SODIMM Memory for Mac | CT8G3S160BM | Crucial.com
Install memory in an iMac - Apple Support
Crucial 8GB DDR3L-1333 SODIMM Memory for Mac - CT8G3S1339M" - Walmart.com