iMac 21.5" A1418 Late 2015 Logic Board 2.8 GHz Core i5 16GB Ram || NO - Part Haven
Apple iMac A1419 mid 2015 w/ Retina 5K display 27" - 32GB Ram - 1TB Solid State 885909925797 | eBay
Amazon.com: Late-2015 Apple iMac with 2.8GHz Intel Core i5 Quad-core (21.5-Inch, 8GB RAM, 1TB) (Renewed) : Electronics
OWC Tears Down iMac Retina 4K, Confirms Memory Is Soldered
upgrade - iMac 27" Late 2015 - what ram to buy? - Ask Different
2015 - 27" Retina iMac, 3.2GHz Quad Core i5 Processor, 16GB RAM, 1TB F – The Apple Xchange - Preowned Apple Products and Services
Install memory in an iMac - Apple Support
Memory Upgrades for iMac w/ Retina 5K Display Late 2015
5K iMac (Late 2015) RAM Upgrade - YouTube
iMac RAM upgrade: Here's an affordable way to improve multitasking - CNET
A-Tech 16GB (2x8GB) 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
OWC 8GB (2 x 4GB) PC12800 DDR3L 1600MHz SO-DIMMs Memory Compatible with 2011-2015 iMac, 2011-12 Mac Mini, and 2011-2012 MacBook Pro (Non-Retina Display) Models (OWC1600DDR3S08S) at Amazon.com