The 6139 is a movement with great features. It’s a 17-jewel automatic with quickset day/date function, chronograph seconds and a 30-minute register with a frequency of 21,600 bph. There is no continuous second’s hand on the watch. There is also no hour register, making this a very old-school single register chrono. The crown is pushed in two clicks to change the day, and one click to change the date.
The case of the 6139-7010 measures 41mm with 19mm lugs, making it a fairly large sport watch for the time, and a small to medium watch by contemporary standards. The case has a barrel shape, which flows smoothly around and has no hard edges save the chrono pushers, which stand out. The crown itself has been recessed and is flush to the case. The 6139-7010 features markers dial, making it an anomaly amongst the 6139 and 6138 watches. It’s actually a very simple, almost plain dial. The face is matte black and markers are white. At 3 O’clock position is the day/date window, which is divided into two smaller windows. The day is displayed in either Kanji or English. The bevelled chapter ring on the outer edge has a Tachymeter scale in white text/markings on a matte black surface. Under twelve it reads “Seiko Speedtimer” and then a Seiko 5 shield logo. At 9 O’clock position there is more text that reads “Sports” in italics. The 30-minute counter is at 6 is marked in a thick white circle with breaks for the minutes and numerals every 10 minutes