Bic Orange

As mine is bought in Sweden, it says Svenskt Arkiv on it. As disposable pens go, this is one of the best, and it's far from expensive.

It writes very well, with a good line and a nice blue colour. Recommended, if it's sold where you live.

The text "Svenskt Arkiv" on it means it's approved for archival use in Sweden, the number is the individual approval, as can be seen from this list of what inks, papers etc were approved for Swedish archival use i 1991 (text in Swedish only and latest list I've found on the web) by the Swedish National Testing and Research Institute.

Bic's web page on Bic Orange Fine.