Traveler's Notebook Spine

When you are using Traveler's Notebook (TN), the elastic rope used to fix the inner notebooks will at the same time makes some trouble: it will cut into the edge of zipper case (the big blue one). In the worse case, the rope and the edge of the zipper case will act as two saws, keep cutting each other, and one will break the other in the end.

In order to get rid of this risk, I make this plastic spine:
1. it will keep the rope away from the edge of the zipper case, so both of them are safe;