Gruen | Tank QuadronGruen, founded in 1894, was a pioneering force in American and Swiss watchmaking, known for its commitment to quality, craftsmanship, and innovative design. In the 1920s, as rectangular wristwatches became fashionable, Gruen was among the first to develop movements specifically shaped for these cases, rather than adapting round movements as many competitors did. The Quadron line, launched in 1925, was Gruens first series of rectangular (tonneau