A-Tech 32GB (4x8GB) RAM for Apple iMac Late 2015 27 inch Retina 5K | DDR3L 1866MHz / 1867MHz PC3L-14900 1.35V 204-Pin SODIMM Memory Upgrade Kit at Amazon.com
Apple 21.5-inch 4K iMac Teardown Reveals Upgradeable Kaby Lake CPU And RAM | HotHardware
Install memory in an iMac - Apple Support
Amazon.com: OWC 8GB (2 x 4GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S08P) : Everything Else
Install memory in an iMac - Apple Support
How to upgrade the RAM on the 27-Inch iMac (2020) | AppleInsider
Install memory in an iMac - Apple Support
How to upgrade iMac (2020) RAM and save up to $2000 - 9to5Mac
How to upgrade RAM in the (Mid 2017) 5K iMac and save up to ~$900 [Video] - 9to5Mac