Basis of this page is an interesting article published in Papua Post 4/2003
On February 14, 1966 the decimal system of currency was introduced to Papua and New Guinea. Henceforth payment in PNG was no longer in Sterling currency but rather in dollars and cents. The successful Butterfly definitive series was issued in the new decimal currency. Besides First Day Covers, the post office issued a special First Day Souvenir Card.
Four letters to Germany, that carry the correct rate of 25 cents.