FB Mondial was formed by 4 brothers (Fratelli Bosselli) who started making motorcycles seriously after WWII. They were the folks who showed that a double overhead cam 125cc racer could beat the 2-cycle engines. Their factory racers won the world championship in 1949, 1950 and 1951.
This 175cc racer is a larger version of the 125 and was used for racing in the Italian series. MV Agusta basically copied Mondial and went on to take over the world championship.