All original Seiko chronograph 6139-6012. Well known automatic movement Seiko 6139. Watch is fully serviced. Every function of the watch works perfect.  All parts including dial are original. 
     The Seiko 6139 movement is a mechanical automatic chronograph movement that was first introduced by Seiko in 1969. It is widely regarded as a significant milestone in Seiko's history, as it was their first chronograph movement and one of the first automatic chronograph movements ever produced.
     The Seiko 6139 movement features a column-wheel design, which is a type of chronograph mechanism that is known for its smooth operation and precise timing. It has a 17-jewel construction, which means it has 17 synthetic gemstones strategically placed at various points within the movement to reduce friction and enhance durability. The movement also has a quick-set day and date function, allowing for easy adjustment of the calendar display.
     The Seiko 6139 movement operates at a frequency of 21,600 vibrations per hour (vph) and has a power reserve of approximately 45 hours. It uses a vertical clutch system, which means that the chronograph can be engaged without causing any additional wear on the movement.