These are high-quality notebooks with archival quality paper.
Much of my writing is pen and paper, and it turns out that good paper also matters a lot. I'm perfectly comfortable with cheap paper in a three-ring binder, but I want something much better for travel and for long-term storage. A bookshelf of these little notebooks also look a hell of a lot better than binders.
Pocket ruled notebook ∞
For random writing on the go, I recommend this little notebook.