One of the contenders to the title of first automatic chronograph, the Seiko 6139-600X series of watches are well loved by collectors for a reason. The titular Col. Pogue wore his Seiko 6139-6002 on the NASA Skylab 4 mission, sneaking the watch on in favor of the NASA issued Omega Speedmaster. This example is from November 1969, and has all original parts other than replacement crystal. The condition is excellent. The lume plots are original and intact. The chronograph functions are working flawlessly. The original H-link bracelet fits up to a 6.75" wrist.