The Buser 140 open face calibre features a bimetallic screw balance and a Breguet hairspring. Its lever and escape wheel are made of anodized aluminium, and it may include an option for Reed's regulator, an early two-section regulator for coarse and fine adjustment. The stem is supported by a steel bearing, and the watch is equipped with a two-part crown wheel with a large bearing. Notably, the crown-wheel screw and ratchet-wheel screw are both left-handed. Some of these details were likely designed exclusively for Alpina and Union Horlogere. The watch movement provides stem winding and setting functions, as well as a sub-second feature. It was likely produced around 1915.