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
8GB (2X 4GB) Memory for Apple iMac 27" 2017 5K Retina Display DDR4 PC4 2400 RAM | eBay
Crucial 16GB DDR4-2400 SODIMM Memory for Mac | CT16G4S24AM | Crucial.com
DDR4 2400MHz PC4-19200 for Apple iMac 2017 27-inch w/Retina 5K iMac 18
Apple iMac 21.5" 2017 i5-7360U 2.3GHz 8GB DDR4 1TB HDD OS Monterey - Grade B+ | eBay
Upgrade your iMac 27'' 2017 RAM with MrMemory review - Wim Arys