Heuer (pronounced hoyer) built several thousand of these in contract batches from 1967-1981 for the West German military, replacing Hanhart and other makers. Issued to aid in combat and navigation timing. 3H and T tritium luminous paint symbols used during the 1960s. Similar Sinn 156 were available after production ended on this model. Band, 6645-12-145-6415 Bund. BUNDESWEHR 6645-12-146-3774. Heuer-Leonidas S.A. Biel, Switzerland. Based on the 1916 caliber 23, Valjoux 230. 17 jewels, manual wind, 36 hour power reserve, 18,000 bph, incabloc shock, plastic crystal, water resist 3 ATM. 1550 SG tech manual.