The first "Roman Numerals"
Although the Roman numeral date codes were officially introduced in July 1986, earlier examples are known to exist. These only appear on lighters with flat bases and were first introduced in 1985 with the Roman numeral I.
The only 1985 lighters I have seen with this date code are the 1937 series replicas, which did not have the month of manufacture stamped
1986 flat base lighters with monthly date codes exist as early as April.