-binders-?

Question

what is the difference between a 3-inch binder and a 3-inch "D" binder?

Answer 1

In a binder the rings are mostly round, in a D binder the rings are in D shape.
Makes the pages lay smoother, and the spine of the binder tidier.
The mechanic system is mostly put to the back of the binder, not the spine.
But this also means that you can not just flip the binder over to use the other side as front.