Battery charger or accessory port? What is this part PO installed?

[protokultur]

I bought a modded Hyper and can't figure out what this part is - under the seat and seems to be connected to the battery. My thumb is holding open a cap which covers a small socket with a square plug inside.

Checked the owner's manual but it doesn't show it in the diagram.

[Gilly]

looks like the bmw sized power port.

[Chuckracer]

Powerlet Products - Rugged power outlets, cables and electronics

[protokultur]

Thanks guys. That's it.