3 3/8" X 5 5/8" (86mm X 143mm)

No markings

Picture courtesy George Sukhoff

3 3/8" X 5 5/8" (86mm X 143mm)

No markings

[side view]

Picture courtesy George Sukhoff

3 1/8" X 5 1/2" (88mm X 138mm)

dome inkstamp

{Siemens & Halske}

Picture courtesy George Sukhoff

3 1/8" X 5 1/2" (88mm X 138mm)

dome inkstamp [side view]

{Siemens & Halske}

Picture courtesy George Sukhoff

3 1/8" X 5 1/2" (88mm X 138mm)

dome incuse

{Kornilov}

Picture courtesy George Sukhoff

3 1/8" X 5 1/2" (88mm X 138mm)

dome incuse [side view]

{Kornilov}

Picture courtesy George Sukhoff

3 1/4" X 5 5/8" (90mm X 145mm)

(dome ink stamp)

{Maker Unknown}

Picture courtesy George Sukhoff

3 1/4" X 5 5/8" (90mm X 145mm)

(dome ink stamp) [side view]

{Maker Unknown}

Picture courtesy George Sukhoff