A standard 12.7mm pink ink nylon ribbon. 10m length. Enough to last a few months/years depending on regularity of use.
We would hand-spool this ribbon on 2 plastic GR1 spools (or your typewriter metal spools if you send them to us). It is a high-quality nylon ribbon that lasts 500+ A4 pages.
If you have an Olivetti typewriter and need GR4 spools, let us know after you make a purchase.