Manufactured by G. Longhi
Numerous models were offered from the 1920s or 30s. In 1993 they were still producing components and complete sidecars for Vespa to order.
Costantino Frontalini bought the sidecar division of the Longhi company and produced a limited number the Caesar model in the 1990s.
Several images Moto Guzzi, Lambretta and Galimberti with Longi sidecars are available: search: Longhi
Source: Gespann-Lexikon