Notice: USB 3.1 require a different front panel header than USB 3.0.
The USB 3.1 port interface is using the USB 3.0 pin set and more. It is design to be backwards compatible (will explain later).
There are no official release of the specs for the USB 3.1 header yet (as of this writing), but first motherboard with this is the ROG MAXIMUS IX FORMULA, STRIX Z270I/Z270G etc.
Description:
Length: 50cm
Connector1: Motherboard USB 3.1 Header
Connector2: USB-C Female with Panel Bracket
What's in the Package: 1pcs USB 3.1 Motherboard Header Male to USB-C Female with Back Panel Bracket