A Brief History of the Marque
In 1926 the designer Piero Calcaterra of Milan built a lightweight 175cc two-stroke motorcycle.
The engine block was divided horizontally rather than vertically and the cylinder was integral with the crankcase. It entered production in 1927.
Sources: MC Storico Conti, et al.
There is also a listing by Mauro Columbo for Gnesa-Calcaterra, Milano 1921-1926.