The Alpina 157 is an open face calibre watch movement that features a unique crown mechanism with a rocker bar and a ratchet located on the back side. It includes a crown wheel that does not serve a specific function and it is suspected to have a left-handed ratchet-wheel screw. The movement exhibits different bridge shapes in the 579 and 581 variations. It offers the following functions: stem winding and setting, as well as a sub-second feature.