The Italian electoral law of 2017, colloquially known by the nickname Rosatellum bis or simply Rosatellum after Ettore Rosato, the Democratic Party leader in the Chamber of Deputies who first proposed the new law, is a parallel voting system, which acts as a mixed electoral system, with 37% of seats allocated using a first-past-the-post electoral system and 63% using a proportional method, with one round of voting. Wikipedia