Shortly after the German invasion of Russia in 1941, the Germans introduced the "Panzerwurfmine(L)", an extremely lethal close-quarter HEAT anti-tank grenade that could destroy the heaviest armored tanks in the war. The grenade was tossed overhand to land atop the tank. After release by the thrower, three spring-out canvas fins stabilized it during its short flight. The Panzerwurfmine(L) was lethal, and inexpensive to manufacture, but required considerable skill to throw accurately and was issued only to specially trained infantry tank-killer teams.