SINN board watch of the German armed forces with Flyback-chronograph type NaBo17ZM, Switzerland around 1982, blackened case, screwed down case back, inside-turning bezel, setting of the watch by pusher & winding crown at 6, black dial, luminous indexes & hands, orange hands for central second & minutes counter, rhodium plated movement calibre Valjoux 558, 17 jewels, measures approx. 74 x 61 x 25 mm, overhaul recommended at buyer's expense, condition 2