OWC brand 16GB memory kit at DDR4-2400MHz.
This high performance memory in rigorously house tested to ensure superior quality, compatibility and reliability.
Australian lifetime replacement warranty.

Technical stuff
Speed: DDR4 SO-DIMM 260 Pin
RoHS: Yes
Op Temp: 0C to +85C
Data Rate: PC4-19200
CL: 17
Voltage: 1.2V
ECC: Non-ECC
Module Ranks: Single Rank
High quality PCB
Meets and or Exceeds Apple / Intel Specifications
Warranty Safe upgrade on 27″ iMac using rear memory access port
Specialist installation recommended for A1418 21.5″ iMac as the screen will need to be removed to change memory.