Black plastic sub panel?

Has anyone ever seen one of these before ?

No. Can you post an inside picture?

I agree that would help, maybe even it will show the label on the inside.

If they end up buying the house. A client sent me this asking about it. I have sent it to 2 electricians and they have no idea haha

I have one similar in my shed… That would be about the only place I would use it.

Have a look at GE’s PowerMark Gold 125 Amp 4-Space 8-Circuit Indoor Main Lug Circuit Breaker Panel

Agreed, see them frequently.

Thermoplastic Power Mark - seen it in Mobil homes.