Apple 27" iMac® with Retina 5K display Intel Core i5 (3.1GHz) 8GB Memory 256GB SSD Silver MXWT2LL/A - Best Buy
Install memory in an iMac - Apple Support
CMS 16GB (4X4GB) DDR3 10600 1333MHZ Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac Core I3 3.06 21.5-Inch (Mid-2010) - A28 at Amazon.com
How to Install Ram on the 2019 27 inch iMac and which Ram to Buy? - YouTube
How to Install RAM in an iMac: 5 Steps (with Pictures) - wikiHow
Install memory in an iMac - Apple Support
Amazon.com: OWC 32GB (2 x 16GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S32P) : Everything Else