The kp/31, aka M31 “Suomi” submachine gun was adopted by the Finnish Army in 1931. It was produced by the Tikkakoski company (more commonly known today as Tikka), and in addition to Finnish military contracts they were eager for international sales, either commercial or military. To that end, they offered a number of different options and variations. Two of those were a vertical front pistol grip and a folding bipod, which could be included together or independently. The Finnish police actually bought a small number of each type, and something like 50 to 100 guns were produced and sold with both features together – like this example.
Interestingly, this one ended up in Israel, used by the Haganah during Israel’s war of independence. They were surplussed off in 1970, and this one (along with two others) were reimported into Finland by a collector. As part of their use in Israel, the original Tikkakoski markings were ground off, and an Israeli property stamp added.