The Pentacon Six mount, also known as P6 or Б in Cyrillic, is a medium format lens mount that was likely introduced by KW in collaboration with Carl Zeiss Jena. It is characterized by an external bayonet coupling. This mount is utilized across a variety of cameras, including the Praktisix, Pentacon Six, Exakta 66, Kiev 6C, Kiev 60, Kiev 88CM, Hartblei, and Arax. Lenses for this mount were produced by manufacturers such as Schneider in West Germany, Carl Zeiss Jena in East Germany, and the Arsenal factory in Kiev, Ukraine. The Arsenal factory continues to produce lenses for this mount, with its Arsat 30mm fisheye being particularly recognized for its quality. Hartblei in the Czech Republic and Arax in Ukraine also update and refine these lenses, notably producing a range of tilt-shift lenses with independently rotatable tilt and shift axes.