3 3/4" X 3 5/8" (95mm X 92mm)

No markings

Picture courtesy Bob Berry

3 5/8" X 3 5/8" (92mm X 92mm)

 No markings 

Picture courtesy Bob Berry

3 5/8" X 3 1/2" (92mm X 89mm)

(dome incuse)

{Köppelsdorf}

Picture courtesy Bob Berry

3 1/2" X 3 1/2" (90mm X 90mm)

 No markings 

Picture courtesy Bob Berry