Anyone know info about tis cab?

Hello guys, I recently got two 15 inch bass horns and I don't know anything about them and have never seen some cabs like these on any forum. They are made out of 20-22mm plywood so they are really solid and they are pretty big for a single 15 inch cab. They look like something Martin or Turbo would have made a long time ago.
Does anyone know anything about these cabs?





Cheers!