The Patek Philippe Ref. 3588 was released in 1970s as an ultra-thin or extra-flat automatic watch, made possible by the new Lecoultre base 28 255 movement, the flattest self winding movement at the time. Even at 35mm wide, these watches are only 6mm thick and wear very comfortably. This example is particularly rare due to its guilloche dial with black Breguet numerals.