Totally constructed myself.
Confederation and German Jack 1867–1903 . The Iron Cross on this flag is 2/3 width of flag. For a more rigorous treatment of the height of the Iron Cross across German flags see FOTW: Proportions of the War Ensign and Jack 1871-1935 (Germany)
Flag construction data from FOTW: Jack 1871-1918 (Germany)

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