Although the FNM also operated an electrified suburban network around Milan, steam locomotives were needed for the more distant destinations. A tender locomotive was commissioned to speed up traffic, which should combine good acceleration with a maximum speed of 100 km/h. The order went to CEMSA, whose works in Saronno were located along the route of the FNM.

The four locomotives were apparently based on plans that came from Borsig. The 2-6-4T wheel arrangement was typical of modern passenger tank locomotives and combined good running characteristics with a large firebox and large supplies. The boiler delivered 1,060 hp permanently and 1,200 hp for short periods. The three cylinders, together with the 1,620 mm large coupled wheels, ensured good acceleration.

The locomotives were used to run direct connections from Milan to Como, Varese, Laveno, Erba and Asso. For some other routes, the axle load of 16.5 tonnes was too high. After the main routes had been electrified, these locomotives could not be used on the secondary routes. So they were retired in 1952 and scrapped shortly thereafter.