3 5/8" X 5 5/8" (89mm X 138mm)

(skirt ink stamp)  

{Made by KPM of Berlin}

Picture courtesy Michał Okulicz-Kozaryn

3 5/8" X 5 5/8" (89mm X 138mm)

(skirt incuse)

{Fuerstenberg}

Picture courtesy George Sukhoff