There was also a special type of grenade called the "Nebelhandgranaten" or "Blendkörper" ("smoke hand grenades"), which was supposed to be smashed over an air vent and fill the tank with smoke, widely used by both sides in World War II. Molotov cocktails also saw much use, especially in the Winter War, early tanks (such as the T-26) being very vulnerable to them, but later tanks required a well-thrown bottle directly over the engine compartment to have any effect at all.