Amazon.com: 2017 Apple iMac with Retina 5K Display (27-inch, 8GB RAM, 512GB SSD Storage) (Renewed) : Electronics
Apple iMac 5K Retina 27" Desktop - 4.2GHz Quad-Core i7 - 16GB RAM - 2. – The Refurbished Apple Store
A-Tech 32GB (2x16GB) RAM for Apple iMac 2017 (27 inch Retina 5K & 21.5 inch Retina 4K) | DDR4 2400MHz SODIMM PC4-19200 2Rx8 1.2V 260-Pin SO-DIMM Memory Upgrade Kit at Amazon.com
Install memory in an iMac - Apple Support
Apple iMac 5K Retina 27" Desktop - 4.2GHz Quad-Core i7 - 16GB RAM - 2. – The Refurbished Apple Store
Adamanta 16GB (2x8GB) Memory Upgrade Compatible for 2017 Apple iMac 27"/21.5" Retina 5K/4K or Non-Retina Display DDR4 2400MHz PC4-19200 SODIMM 1Rx8 CL17 1.2v Single Rank RAM DRAM at Amazon.com