My very fat vintage Filofax I snagged on eBay along with some pretty charms. This is a vintage model called the Filofax Cavendish with 30mm rings in the personal size which is
In Praise of 30mm rings
CONVERSION/REPAIR Kit for Personal Filofax & Planer Mulberry 6 Rings 180-6-16P-F | eBay
Filofax Standard Ring Binders A5 A6-personal Pocket Mini and - Etsy
Conversion/Repair Kit for Standard A5 Filofax 6 Rings Binder 30mm 19.19.70.19.1 | eBay