Icebergidesign Frameless Cork Bulletin Board, 20 x 24, Natural Surface

Will darts go through the cork to damage walls?

Can this 24 x 38 cork board be hung vertically?

What is the rubber band for that is included with the hardware?

Is there a pocket of space behind the board's internal framing? How deep is that space, if so? I'm trying to hang this over a built-in to hide it.