Firebox stamp
stamp used between 1921 and 1923 in the Netherlands and the Dutch East Indies for insuring sea mail
en-GB/ˈfaɪəbɒks ˈstæmp/
en-US/ˈfaɪɚˌbɑks ˈstæmp/
stamp used between 1921 and 1923 in the Netherlands and the Dutch East Indies for insuring sea mail