This coin display fits approximately 32 challenge coins. Each coin plank is 15” wide. Instead of securing the planks to the box frame, I secured them using 1.25” screws to the plywood backing. I had made a previous coin display securing the planks using pocket screws, and the planks were a little crooked, so that was my reason for securing them to the backing. Each plank has exactly 2” of space in between. This allowed for various coin sizes to fit with no problem. Rabbet for coin is 1/4” from what I recall. Thanks!