What kind of power port is this?

I'm planning on getting a new PSU and I was shopping online when I saw this thing.

What kind of port is this? I've never seen it before, and I definitely can't find cables for this.

For reference, this is a "normal" 3 prong cable:

The PSU itself is a NZXT HALE90 850W.

It would appear that is a IEC 320 C19 coupler.

This coupler is used for some IT applications where higher currents are required, as for instance, on high-power workstations and servers, uninterruptible power supplies, power distribution units, large network routers, switches, blade enclosures, and similar equipment.

For North America you could use a NEMA 5-15P to IEC 320 C19 cable like this one (for example).