Chess/Backgammon Board

I am looking for any information about this game set. It was bought at a yard sale from and elderly gentleman (80ish years) who stated it belonged to his parents and had been sitting in his attic. I am unsure of the materials it feels like a porous stone.

The board is hinged with a Chess/Checker board on the inside and the outside is inset with a backgammon board when folded open.

Measurements:
Full Board: 20.5" X 12.5"

Checker Pieces are 1" circumference
Chess Pieces start with the King and 1.5" tapering down to Pawns at 1"