Today in Postal History

The Cook Islands group which includes Aitutaki is spread
out over a large area of the Pacific northeast of New Zealand.

This cover, albeit philatelic, was franked with
two stamps based on similar designs used in Rarotonga.
The two stamps are ½ penny black and green
most probably from the 1927 issue (SG 30).
Gibbons values these stamps on cover 6 times or more the value of used singles.