World War II Thermite and white phosphorus cause some of the worst and most painful burn injuries because they burn extremely quickly at a high temperature. In addition, white phosphorus is very poisonous: a dose of is lethal to the average human. Molotov cocktail The Molotov cocktail is an improvised incendiary grenade made with a glass bottle typically filled with gasoline (petrol), although sometimes another flammable liquid or mixture is used. The Molotov cocktail is ignited by a burning strip of cloth or a rag stuffed in the bottle's orifice when it shatters against its target which sets a small area on fire. The Molotov cocktail received its name during the Soviet invasion of Finland in 1939 (the Winter War) by Finnish troops after the former Soviet foreign minister Vyacheslav Molotov, whom they deemed responsible for the war. A similar weapon was used earlier in the decade by Franco's troops during the Spanish Civil War. A humorous nickname given to the Soviet cluster bombs was "Molotov bread baskets" in Finland. Practice (simulation) Practice grenades are similar in handling and function to other hand grenades, except that they only produce a loud popping noise and a puff of smoke on detonation. The grenade body can be reused. Another type is the throwing practice grenade which is completely inert and often cast in one piece. It is used to give soldiers a feel for the weight and shape of real grenades and for practicing precision throwing. Examples of practice grenades include the K417 Biodegradable Practice Hand Grenade by CNOTech Korea. Design Various fuzes (detonation mechanisms) are used, depending on purpose: ImpactExamples of grenades fitted with impact fuzes are the German M1913 and M1915 Diskushandgranate, and any British grenade fitted with the "All ways" action impact fuze such as the No. 69 grenade, No. 77 grenade and No. 82 grenade (Gammon bomb). Timed fuzeIn a timed fuze grenade, the fuze is ignited on the release of the safety lever, and detonation occurs following a timed delay. Timed fuze grenades are generally preferred to hand-thrown percussion grenades because their fusing mechanisms are safer and more robust than those used in percussion grenades. Fuzes are commonly fixed, though the Russian UZRGM () fuzes are interchangeable and allow the delay to be varied, or replaced by a zero-delay pull fuze. This is potentially dangerous due to the risk of confusion. Pull (instant) fuzeA pull fuze is a zero-delay fuze used in booby traps: the grenade detonates immediately when the striker retaining pin is removed. The pin is typically attached to a tripwire. Beyond the basic "pin-and-lever" mechanism, contemporary grenades have safety features. The main ones are the safety clip and the bent end of the safety pin. The safety clip was introduced in the M61 grenade (1960s, Vietnam War), and is also known as the "jungle clip" – this provides a backup for the safety pin, in case it is dislodged, notably by jungle flora (plants and vegetation). This is particularly important because the safety lever is often used as a carry hook, despite the obvious danger this poses. The bent end of the safety pin increases the force required to remove it, reducing the risk of accidental arming. The 2016 US ET-MP uses a user-settable timed electronic fuze. Manufacturing Modern manufacturers of hand grenades include: Agenzia Industrie della Difesa (Italy) Diehl (Germany) Mecar (Belgium) Rheinmetall (Germany, formerly Arges, Austria) Ruag (Switzerland) Nammo (Norway) Instalaza (Spain) Solar Industries (India) Operation The classic hand grenade design has a safety handle or lever (known in the US forces as a spoon) and a removable safety pin that prevents