On the plain black Montblanc fountain pens of the 1970s, the number of cap rings is the most important distinguishing feature. A single ring engraved “MONTBLANC GERMANY” marks the simpler specification; together with a plain 585 nib this is as a rule a 320, made between 1971 and 1977. Two cap rings indicate the better version; if the nib additionally carries the Montblanc logo and the marks “14k/ct” and “585”, that points to a 221, in production from 1971.
The collectors' sources disagree about when production ended: for the 221 both 1979 and 1988 are given, with the line continuing in modified form into the early 1990s. Dating to the decade is therefore sounder than dating to the individual year.
Both models belong to the everyday range of the years before Montblanc reinvented itself as a luxury brand. They are solidly built working pens with a gold nib, but they fetch only modest prices on the collectors' market.