I space that I wanted to put this I had to mount it vertically, instead of horizontal, so I was a bit worried because of the pen holder.
I was able to remove the pen holder and mount it below the dry erase board and mount it vertically without too much trouble.
It now fits the space great and is a nice piece for the price.
The "Key Holders" are a little flimsy, and I would only count on it to hold the marker.