A Brief History of the Marque
The Santagostino brothers built motorcycles fitted with JAP and Blackburne engines of 350 and 500cc.
A 1922 Modelo Super 132cc two-stroke has "Royal Super" embossed on the rhs engine cover, so they may also have built their own engines. This model has chain drive from the engine, a second chain for the pedals, and a hand change on the petrol tank. There is no evidence of a front brake, but it may have had a drum rear brake activated by a lever on the handlebar.
Sources: MC Storico Conti, et al.