Works in my 2017 27" iMac (it might not work if you mix it with the original Apple memory, though.
This way I would keep the original 8+8 and have 48 Gb Ram total which is more than enough for my needs.
I would guess if I had replaced the 8+8 with the 16+16 it would probably work but I didn't try that because it requires removing the back cover.
The product works well in that computer.
I've read about people having to go into the BIOS but for me, it just worked immediately and I confirmed that I had the appropriate amount of installed RAM in the System section.
Ran the ram test and short enough one of the ram was faulty.
Kingston Technology HyperX Impact 8GB Kit (2 x 4GB) 2133MHz DDR4 Laptop Memory HX421S13IBK2/8 Brought this to use with my Intel NUC and after a month and a half of usage, I am plagued crashes and multiple blue screen reboots stated errors with memory management among with other errors.
Took out one of the memory sticks and the problem went away.
It's now outside of the return window and I'm stuck with only 16gb ram... sucks.
Need to reseat it to see if it is a hardware issue.