This replacement sensor for the Millennium and Millennium 2 Chronograph comes complete with a 20 foot shielded cable. The sensor for the Millennium 2 chronograph is 40% more light sensitive than the M1 sensor for accurate readings in lower light atmospheres. Sensors for the Millennium Chronograph are gray and must be matching to work with the Millennium Chronograph. Sensors for the Millennium 2 Chronograph are blue and must be matching to work with the Millennium 2 Chronograph. Sensors work with each chronograph, but only when paired with a sensor of the same color. Millennium and Millennium 2 sensors will not work together.