China. (Indo-Chinese Post Offices In Hoi-Hao). 1907. Registered envelope addressed to Hanoi bearing Hoi-Hao Yvert 46, 2f violet/orange tied by 'Hoi-Hao-Chine' double ring with boxed hand-struck 'R' routed via Haiphong with Hanoi/Tonkin receiver. Very scarce stamp on cover.