Thanks for your reply. The David Allen Company paper-based products are excellent and a good starting point for someone new to GTD - everything's laid out for you and you're up and running quickly. I originally started with the full-size binder and then down-sized to the smaller format because I walk around a bit between buildings.
As I've been doing GTD since 2006, my paper-based system has morphed quite a bit (additional tabs), so I needed a thicker 7-ring binder. I lucked out because I still had my classic-size 3" leather binder from my Franklin Planner days, which just needed a dusting.
As for tabs, if you purchase additional ones, I'd recommend the Avery 5 1/2" by 8 1/2" Durable Write-on Plastic Dividers #16180 which come 5 to a pak -- assuming you're going with smaller format. Reason being is that the tab has strong bending resistance and is wide enough for a printed label.
I created a mini portable InBox by purchasing pockets from the same brand - one pocket to house my cut-up scrap letter-sized paper (which I hand tear into 4 squares) and another pocket for the actual InBox.
To carry the Templates around, which I find useful for review and my Weekly Review Checklist, I purchased sheet protectors from the same brand.
Best of luck in your GTD practice.
Thanks for the detail Paul. Very cool. I was also thinking about re-enlisting some old franklin binders.