Just got this in today been waiting two weeks for this. A Zenith Special Pilots watch from the 1930. Was looking at Helvetia for this style on Ebay all junk cases beat to hell and got this from a seller in Czech republic for about the price the junk going for on fleabay. This is running like a top not bad size at 41mm from the serial number on the movement made in1930.
When you take the metal case back cover off there is a glass cover over the movement and a cool regulator.