The reference 3445 was launched in 1961 through 1981 and was the first calendar wristwatch to be offered by Patek Philippe in series. The 3445 features a screw back case, automatic movement and subsidiary seconds at 6 oclock. The preset example was retailed by Cartier and is signed Cartier on the dial. Behind the 11 oclock lug has the retailers hand stamped number which is common. The movement is also stamped, HOX, indicating this watch was meant for the American market. Cartier signed Patek Philippe watches are very rare and this is a great opportunity to get a nice one.