A wristwatch is highly desirable for collectors because of its rarity and those details in the case, the dial and the numerals which denote the evolution of style and design. It is the constant search towards an always more refined style, preceding the trends, positioning the product at the avant-garde of the market, that motivates manufacture designers to create unique models as market testers or as special orders from clients. After our research on this Patel Philippe half-hunting cased wristwatch, it transpires that in our 27 years of auctions, and with a grand total of 37 years of experience among our in-house experts, never have we seen nor heard of a Calatrava wristwatch with half-hunting case made by Patek Philippe. Montres bracelets a couvercle Shortly after 1920, wristwatches were selling better than pocket watches. Most eminent designers and makers were keen to find, for sport and everyday wristwatches, an equivalent to the popular hunting cased pocket watches which could easily be personalised with a monogram or enamelled decoration on the cover. Cartier and Verger, in France, used improvements such as the guillotine with sliding shutters, already invented for dress watches, and Leon Hatot, with the Montle bracelet ouvrante having a spring loaded hinged cover, presented his own solution. The latter ' s solution was also adopted by most of the Swiss designers such as Wenger, Niton as well as those working for Vacheron Constantin and Patek Philippe. In this respect, one of the most successful solutions was that of the celebrated Reveao invented by Rene Chauvot (French Patent No. 712868 from March 4th, 1931), first produced by Fontainemelon S. A., often retailed by Gimbel in, then acquired by Jaeger I,eCoultre. The cases of most of the watches with concealed cdial, produced helween 1920 and 1935, were of high quality, often with engraved decoration on the band and bezel, the cover sometimes made in two-coloured gold with geometrical decoration in an Art Deco pattern.