Very cool and one of the earliest waterproof rectangular or tank shaped cases we've seen. The movement sits in a solid block of stainless steel which is inserted up into the stainless steel case and seals against the crystal with two screws from the back. From the looks of the clean factory original dial and the crisp clean original Kelbert movement inside, it was a sound design. Nice big 28mm x 36mm tank all stainless steel case is is superb condition with no scratches or damage. Factory original dial in a pale honey tone with gold leaf trim and Roman numerals at 3, 6, 9 and 12 with the original hands in blued steel. The original luminous material is an exact color match between the dial and minutes hand but for some reason the hour hand fill has yellowed over time. The dial is signed Kelbert Waterproof Antimagnetic Shockabsorber. Original crystal is clean and clear. Kelbert signed 17 jewel manual wind movement is clean and corrosion free and is keeping good time. This is a very high quality military watch and we were told by the estate that it was worn through WW2 by a U.S. Naval Officer. Fitted with a new brown lizard-calf 18mm strap. Very cool.