Thermos bomb

The Thermos bomb, formally the AR-4, was an Italian air-dropped anti-personnel mine of the Second World War, nicknamed for its resemblance to a Thermos vacuum flask. The cylindrical device was about 31 centimeters long and weighed roughly 3.68 kilograms including its TNT filling, and its motion-sensitive fuze could detonate if the bomb was disturbed after landing, with a later version adding a delay fuze that could go off sixty to eighty hours after arming. The Italian Air Force dropped large numbers of them against Malta and across the Middle East theater, and because unexploded examples were so dangerous to move, disposal crews typically destroyed them in place rather than attempting to defuse them.