After trying a whole bunch of pocket notebooks, the Apica A7 has become my go-to.
It’s 2.8 x 4 inches (10.2 x 7.1 cm), which is quite a bit smaller than your typical Field Notes-sized notebook. However, I’ve come to really like it better at this size. I’m rarely writing prose in these notebooks; I’m always writing short lists. So I usually don’t take up a full line anyway. This tiny size leaves less wasted space on the page. It’s also small enough to fit in a shirt pocket, whereas Field Notes often doesn’t.
I’ve also been using the regular old Fisher space pen with it. I usually prefer something I can use one-handed, like a clicky or bolt-action, for my daily pocket pen, since it makes jotting things down that much quicker. But the size and simplicity of the space pen’s design is just really satisfying sometimes.
Damn, I've never considered that such a tool could exist! I've got all kinds of stuff to look into now. Do you use your notebook for sketches or writing? Is there a particular reason you chose to begin carrying one?