Patek Philippe & Co. (PP) is a Swiss ultra-luxury watch manufacturer founded in 1852, located in Geneva and the Vallée de Joux. It designs and manufactures timepieces and movements including some of the most complicated mechanical watches. It is considered by many experts and aficionados to be one of the most prestigious mainstream watch brands along with Audemars Piguet, Vacheron Constantin, and A. Lange & Söhne. Polish watchmaker Antoni Patek started making pocket watches in 1839 in Geneva, along with his fellow Polish assistant Franciszek Czapek. They separated in 1844, and in 1845 Patek joined with the French watchmaker Adrien Philippe, inventor of the key-less winding mechanism. Patek Philippe & Co was founded in 1851. Patek Philippe pioneered the perpetual calendar, split-seconds hand, chronograph, and minute repeater in watches. Like other Swiss manufacturers, the company produces mostly mechanical movements of the automatic and manual wind variety but has produced quartz watches in the past, and a digital wristwatch, the Ref. 3414. Patek was notable for being one of 20 Swiss watch companies to develop the first Swiss production watch the beta 21 used by other manufactures in watches such as the Omega Electroquartz watches.