This one is a gorgeous smooth leather compact organizer. Very professional, businesslike, unisex and slips easily into places a bulky personal would not go.
This is a Swedish brand and it has the most wonderful refills – very different do to lists (three different kinds) and other wonders like project management pages.
You could use it as a wallet as well – it has several slip pockets (one lovely one on the outer inside cover edge) and a zippered pocket.
I also like the slip clasp. There is no press stud – you slide the strap through the loop. So there is room for expansion and it feels lovely and smooth to slip the strap in and out instead of pushing down on a popper, as you usually do.
Edited to add: these rings attach to the back of the binder with Velcro and so if you had these Velcro backed rings you could put in and take out different sets of rings with different sets of inserts, depending on your needs.
A commenter on this post left the following comment (thank you Petter!):
This binder is a ProPlan binder, a band that Almanacksförlaget launched in the early 90s (or even earlier). They were made for a ring-bound calendar refill to be slipped into the long slot on the left side of the leather cover, and then the rings themselves had a velcro backing, so you could, in theory, have different sets of information on different rings, and just put the set of information you required into the rings. Almanacksförlaget also did a budget version called ProGenda, where the ring-bound calendar-refill went onto the rings in the binder rather than in the leather cover. I remember having one of these as a kid, and it came with a handbook, telling you how to use abbreviations etc on both your calendar and your todo list/other info pages to link them together.