This is the straight support for the card barrier in the third edition of the great board-game Catacombs by Elzra.
The problem I found with the card barrier that it always wanted to swell and take space on the table. The guides firm up the barrier and keep it straight.
Four are needed for one setup.
Here is a link to the Board-game geek site for the game:
https://boardgamegeek.com/boardgame/195137/catacombs-third-edition