Amazon.in: Buy OWC 32GB (2 x 16GB) 2400MHZ DDR4 SO-DIMM PC4-19200 Memory Upgrade for 2017 iMac 27 inch with Retina 5K Display, (OWC2400DDR4S32P) Online at Low Prices in India | OWC Reviews
Differences Between Late 2015 iMac Retina 4K/5K Models: EveryMac.com
Install memory in an iMac - Apple Support
Memory Upgrades for iMac w/ Retina 5K Display Late 2015
Install memory in an iMac - Apple Support
Install memory in an iMac - Apple Support
Timetec 16GB KIT(2x8GB) Compatible for Apple Late 2015 iMac (27-inch w/Retina 5K Display)
CMS 32GB (4X8GB) DDR3 12800 1600MHz Non ECC SODIMM Memory Ram Upgrade Compatible with Apple® iMac Retina 5K 27-Inch (Mid 2015) Mf886Ll/A - A6 at Amazon.com
Apple iMac Retina 5K Late 2015 - Core i5 3.3Ghz 27Inch Desktop DDR3 RAM Memory | Kingston