RAM & Memory Upgrades
64GB (2 x 32GB) DDR4 2666MHz PC4-21300 260-PIN SODIMM MEMORY RAM KIT COMPATIBLE WITH 27" RETINA 5K IMAC (2019/2020)
SIZE/CAPACITY: 32GB KIT (2 x 32GB) VOLTAGE/POWER CONSUMPTION: 1.2v CAS LATENCY: CL19 SPEED: PC4-21300 (2666MHz) TYPE/INTERFACE: 260-PIN DDR4 SODIMM IMAC 2019
https://www.bizrate.co.uk/ram_memoryupgrades/64gb-2-x-32gb-ddr4-oid10298907453.html