I am not sure if Gruen company still exits, but these are the information which I have found from the internet.
The watch that I like is the 1928: The Techni-Quadron "for exact time in seconds" aka the Doctor's watch. The “Doctor’s Watch” was distributed under the names of Alpina, Gruen, Alpina-Gruen and Rolex (“Prince”). But the infatuation had only a short duration.
The famous Techni-Quadron "doctor's watches" are so-called because the large seconds dial was handy for timing a patient's pulse. These were not sold only to doctors, however. The watch was advertised as a timepiece for technicians and "radio and mechanical engineers"—anyone who needed to measure time in seconds. The 877 movement, manufactured by Aegler in Biel, was also used in the Rolex Prince; this unusual movement gives the watch its distinctive "dual dial" design. Hours and minutes are confined to the upper half of the dial, while the entire lower dial is dedicated to seconds. The Techni-Quadron provided a useful alternative to the tiny seconds hands on most watches from this era, which can be as little as 2mm (one tenth of an inch) long, and are not practical to use for timing.
Below picture left is the Alpina Gruen, together with the Rolex Prince. After the start of the Depression, 1930 an arrangement was made with Alpina, with the production of a dual branded Alpina/Gruen watch.
Top photo: All Techni-Quadron models have a long case and a large seconds subdial, as large (or nearly as large) as the hour/minute portion of the dial. The "dual dial" layout is a distinctive feature of this line. This particular watch is slightly unusual—most have dials that are more functional and less ornate. Compare this dial to the catalog illustration below, which is more typical. (Photo courtesy of Jack Goldberg.)
The Techni-Quadron does not have the hour and minute hands attached at the center of the dial— as other watches do—on the contrary, these hands are attached above where the crown enters the case. The seconds are in their own subdial, which is symetrically placed outside of and below the hours/minutes portion of the dial. Because these watches are sought after by collectors, other models are often represented as Gruen "doctor's watches" when offered for sale.
The Techni-Quadrons were extremely accurate, and like other Quadron models, did well in European chronometer tests.
Some Techni-Quadron models originally came with "expanding buckles." These look nearly identical to modern deployant buckles, but their purpose was different. With the buckle closed and locked, the watch could be worn normally. However, if the buckle was unlatched, making the strap loose, the wearer could slide the watch up the arm until it fit snugly just above the elbow, keeping the hands and wrists free. A 1929 advertising photo shows a doctor wearing his watch this way. These buckles were available on metal mesh bracelets or leather straps. A smaller version of this buckle was offered for women.
Above: An illustration of a Techi-Quadron with an "expanding buckle" from the 1929 catalog. The buckle allows the watch to be worn either normally, or above the elbow, as shown in the photo.
After Gruen moved all production to the Precision Factory and stopped buying movements from Aegler, they made some dual-dial watches that are superficially similar to the Techni-Quadron, using modified versions of Gruen's calibre 500.
Gruen, Rolex and AeglerOne of the most deeply-held myths about Gruen is that Gruen and Rolex at one time manufactured movements for each other's watches. This is not true, although both firms did use some of the same movements—the best known examples are the Gruen Techi-Quadron and its twin, the Rolex Prince. In reality, these movements were manufactured by a third company, Aegler, who was a very close neighbor to the Gruen Precision Factory.
