This is a blank Blue Sea 360 Series panel with a cutout to fit a standard dual receptacle. It would typically be used to mount a GFI receptacle.
Another version of this panel (p/n 1479) comes with a standard receptacle already installed but with this version the outlet is not included. You could get your own standard receptacle in a different color, grey would be good, or use a GFI receptacle
Height:4.75in (120.65 mm)
Width:4.88in (123.95 mm)
Depth:1in (25.4 mm)
Weight:0.33lb (0.15 kg