The Jymy class motor torpedo boats or J class was an Italian-designed class of motor torpedo boats, seeing service during World War II with the Italian Navy in the Lake Ladoga, and later with the Finnish Navy in the Gulf of Finland. The four boats of the J class were built by Cantieri Baglietto in Genoa, Italy and transported to Finland over land and sea. The ships were initially used by an Italian contingent, the XII Squadriglia MAS, who served in Lake Ladoga during the sailing season of 1942. The Finns bought the boats on 5 May 1943 in Tallinn and transported them to Finland.