Stridsvagn m/21 (Strv m/21) was a Swedish development on the German World War I tank prototype LK II.It was powered by a sleeve valve type engine located in the front, the driver and crew being in the rear. The suspension and running gear was protected by armored skirts. Ten of these tanks were built and were armed with a single 6.5 mm machine gunThe Strv m/21-29 was an upgraded version of the m/21. The modifications included a more powerful engine and heavier armor.