OWC 16GB (2x8GB) ram Upgrade PC3-12800 DDR3L 1600MHz sodimm 204 Pin CL11 Memory Upgrade Kit Compatible with Late iMac, Mac Mini, and MacBook Pro Computer at Amazon.com
How to upgrade the RAM on the 27-Inch iMac (2020) | AppleInsider
How to Upgrade the Memory in the iMac Pro (late 2017) - YouTube