This is the adapter you will receive.
Motherboard Header Location:
Plug the adapter into the 20 pin connector shown below marked B (Internal Common IO header). Location of this header varies across different models.
Image courtesy "Intel NUC Kit NUC8i7HV Technical Product Specification"
List of compatible NUC models:
V_USB is the voltage detected by the adapter to check if PC is on after holding PWRBTN low.
5Vsb is the voltage that powers on the adapter.
All GNDs are internally connected.