The CB class was a group of midget submarines, designed and built by Caproni for the Italian Navy during World War II. CB-20 was captured by Yugoslav partisans in Pola at the end of the WWII. It was then pressed into active service in the Yugoslav Navy from 1950 to 1957 as P-901. The sub was donated to the Nikola Tesla Technical Museum in Zagreb in 1959 where it is now on display.