For many watch lovers, a hand-wound movement represents the purest form of a mechanical watch: no rotors hide the movement, and the regular winding becomes a beloved ritual. Thus we are extremely pleased to present to you with the 903 Classic and 903 H4 two navigation chronographs with the rare Lemania 1883 hand-wound movement. Together with their perfect readability, clear arrangement of functions and ease of use, they also possess characteristics that users of a watch with a slide rule function need to carry out mathematical calculations. Moreover, with the use of such an instrument comes the good feeling of practicing an art of technical calculation that few people have mastered these days. Both models are practical instruments with which practically anything can be calculated - and which permit their wearers to show off their expertise and style. While they are identical with regard to suitability for everyday use, durability and state-of-the-art technological features, they differ in appearance due to the various colors of the minute and hour counters, the little second counter and the bezel. The value of these watches is enhanced by the fact that the Lemania 1883 hand-wound movement is no longer made. This may intensify the desire to possess these watches - not only among watch collectors.