Hi HTx,
This is a very nice design.

These were local stamps issued for Christmas Island in the Line Islands in the Pacific, now part of Kiribati.
Originally there was no post office on the island and the stamp paid for delivery to another island, often Papeete in Tahiti so combination covers exist.
5c stamps in this design were first produced in 1916 when various countries appear to have had half-hearted claims on the island.
The island was attached to the British colony of the Gilbert and Ellice Islands in 1919 and remained part of the colony until the colony became independent as Kiribati and Tuvalu.