Appears to be an IEC320-C8 panel receptacle. Some come keyed with the square on one side, others are round on both pins (non-polarized).
Typical square on one side could be: 770W-X2/13 by Qualtek
Appears to be an IEC320-C8 panel receptacle. Some come keyed with the square on one side, others are round on both pins.
Typical square on one side could be: 770W-X2/13 by Qualtek