Apple's New 21.5 Inch iMac Has Upgradeable Parts — That's a Huge Deal
How to Upgrade/Install Memory in a 21.5-inch iMac (Mid 2017) iMac18,1 iMac18,2 - YouTube
HOW TO UPGRADE NEW 2017 IMAC RAM - YouTube
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
Can you upgrade the RAM in the 27-inch iMac? | iMore
How to upgrade RAM in the (Mid 2017) 5K iMac and save up to ~$900 [Video] - 9to5Mac
21.5 inch late 2013 iMac - RAM upgrade - Apple Community
A-Tech 16GB (2x8GB) RAM for Apple iMac 2017 (27 inch Retina 5K & 21.5 inch Retina 4K) | DDR4 2400MHz SODIMM PC4-19200 1.2V 260-Pin SO-DIMM Memory Upgrade Kit at Amazon.com