They were locomotives for fast passenger trains and most came from the Società per le strade ferrate dell'Alta Italia (SFAI).

The oldest were delivered from Koechlin of Mulhouse between 1873 and 1874 and accounted for more than half of the total quantity.

The subsequent orders, made by RM, were to Maffei of Munich who delivered them between 1884 and 1889.

In the FS locomotive list, at 31 December 1914, 60 units were registered.

They were divided into two groups with different technical characteristics and some functional and aesthetic variations.